tours:faq
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tours:faq [2019/03/18 16:15] constan [How LONG did it take to build the NSCL/Cyclotrons/other equipment?] |
tours:faq [2024/05/30 09:23] (current) constan |
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| ===== Questions with Incomplete Answers ===== | ===== Questions with Incomplete Answers ===== | ||
| - | ==== How much water does the laboratory use? ==== | + | ==== Fun facts about FRIB ==== |
| - | //(from Brad Bull)// Our estimated annual usage is about 36M gallons. Peak is 250k a day during the hottest time of year. Most of the water is used for evaporative cooling (cooling towers). | + | * The world-leading rare isotope facility, with the most powerful heavy-ion beams |
| - | + | * Accelerates heavy ions to ~50% of the speed of light | |
| - | ==== What will happen to the cyclotrons when they are removed to make way for the FRIB linac? ==== | + | * Produces rare isotopes that are radioactive and short-lived; never found on Earth, but stars make them! |
| - | //(from Brad Sherrill)// | + | * Is expected to discover ~1000 new isotopes (varieties of elements that have never been observed) |
| - | They might be repurposed for other research at MSU. There are no plans to send them anywhere. | + | * Serves over 1800 researchers from 50+ countries |
| - | + | * Facility consists of four buildings, 565,000 gross square feet | |
| - | ==== Can I get a tour of the FRIB tunnel? ==== | + | * Underground tunnel: 570 feet long, 70 feet wide, 13 feet high; floor is 32 feet underground |
| - | //(from Jessica Kolp and Rebecca Abel)// By appointment, after 3:30pm, groups may schedule a public tour starting at FRIB Trailer #6. For the safety of our visitors, the following rules apply for FRIB construction site tours: | + | * Total Project Cost: $730 million, mostly funded by the US Department of Energy Office of Science |
| - | * Closed-toe shoes or work boots required (no high heels, athletic/tennis shoes or sandals) | + | * Home to the #1 US nuclear physics graduate program |
| - | * Long pants required (no shorts, capris, or dresses) | + | * Began operation in May 2022 |
| - | * Must be more than 16 years old | + | |
| - | * Safety gear will be provided | + | |
| - | + | ||
| - | ==== Fun FRIB facts ==== | + | |
| //(from Brad Bull's Staff Info talk 6/24/17)// | //(from Brad Bull's Staff Info talk 6/24/17)// | ||
| * Concrete: ~35000 cubic yards | * Concrete: ~35000 cubic yards | ||
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| * that soil would make a mountain 175 feet high | * that soil would make a mountain 175 feet high | ||
| * Much off-side fabrication (two sites in Lansing) sped up work | * Much off-side fabrication (two sites in Lansing) sped up work | ||
| - | * Power consumption: 18 MW | + | * Power consumption: 14 MW |
| - | * Final square footage: 580,000 (double what NSCL was before) | + | |
| * Planning, design, and construction are only 10-20% of total cost of ownership! | * Planning, design, and construction are only 10-20% of total cost of ownership! | ||
| - | ==== What is the heaviest rare isotope beam ever studied at NSCL? ==== | + | ==== Why is the cycstopper standing on end, rather than lying flat like the K500/K1200? ==== |
| - | Tellurium-134. | + | //(from Stefan Schwarz)// Main technical reason: the cyc-stopper is better at accepting large beams (in terms of emittance, i.e. beam width times angle) in its axial = horizontal direction, as built. |
| + | A bit of background: for the beam to stop efficiently in gas stoppers, it needs to have less energy spread than what we typically get from the A1900. | ||
| + | |||
| + | To reduce that energy spread we use what’s known as momentum compression, i.e. the process of removing longitudinal energy spread with the help of a dispersive element (big dipole magnets in N3/4) and matched wedge-shaped degraders. However, since we bend/disperse the beam horizontally, the beam quality suffers in that plane. The cyc-stopper’s acceptance is higher in the horizontal direction when ‘standing’, so it’s able to make up for the larger beam emittance in that plane. | ||
| - | ==== What kind of controls are used? ==== | + | There are also practical reasons: as built, the stopped beam will come out on the fixed south side of the magnet through the central bore. It’s a lot easier to construct an extraction beam line with this concept than taking the beam out through the top or bottom half in a ‘flat’ orientation. Also, access and work on the low-energy ion guides (carpets, conveyor) is a lot easier that way. |
| - | //(From the NSCL website)// EPICS - Experimental Physics and Industrial Control System is a distributed control system that was written jointly by LosAlamos an Argonne National Laboratories. It is also the control system used to control and monitor the NSCL Control system and beamlines. The NSCL data acquisition system has a certain level of support for accessing EPICS. This support gets built if the EPICS base software can be located at configuration time when the NSCL DAQ software is built and installed. Please note that the NSCL data acquisition group has also written a more complete EPICS access package, with Tcl/Tk EPICS aware widgets that is distributed seperately. That software is tested on Linux, Windows as well as MAC OS-X. | + | |
| + | FYI, we entertained the ‘flat’ orientation for a while in the early design phase, but for the reasons outlined above, we gave up on that rather quickly. | ||
| + | |||
| + | ==== How much water does the laboratory use? ==== | ||
| + | //(from Brad Bull)// Our estimated annual usage is about 36M gallons. Peak is 250k a day during the hottest time of year. Most of the water is used for evaporative cooling (cooling towers). | ||
| + | |||
| + | ==== What will happen to the cyclotrons now that they are replaced by the FRIB linac? ==== | ||
| + | [[https://frib.msu.edu/news/2023/chip-testing|K500 refurbishing for chip testing]] | ||
| ==== How much did all this cost? ==== | ==== How much did all this cost? ==== | ||
| - | //(From Sam Austin's book, //Up From Nothing//)// Total funding to the lab from 1962-2008 has been $664.5 million in 2014 dollars. There should be another ~$100 million in funding by the time the CCF is shut down. Since the FRIB project costs about $730 million, the funding for cyclotrons at MSU just about equals it. | + | //(From Sam Austin's book, //Up From Nothing//)// Total funding to the lab from 1962-2008 has been $664.5 million in 2014 dollars. The lab used ~$100 million by the time the CCF was shut down. The FRIB project cost about $730 million. |
| ==== In addition to traditional CNCs and machining techniques, does the lab use 3D printers to manufacture custom parts? ==== | ==== In addition to traditional CNCs and machining techniques, does the lab use 3D printers to manufacture custom parts? ==== | ||
| - | Because most of our parts are metal, 3D printing isn't yet useful for many purposes. However, NSCL now has enough demand for plastic parts that we have one 3D printer working constantly! | + | Because most of our parts are metal, 3D printing isn't yet useful for many purposes. However, FRIB now has enough demand for plastic parts that we have multiple 3D printers working regularly! |
| ==== What is the advantage of higher energy for FRIB? ==== | ==== What is the advantage of higher energy for FRIB? ==== | ||
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| ==== The average experiment produces how much data? ==== | ==== The average experiment produces how much data? ==== | ||
| - | From hundreds of gigabytes to several terabytes! | + | 100 terabytes is a good example |
| ==== How big is the building? ==== | ==== How big is the building? ==== | ||
| * 1964: The original building was 30,000 square feet. | * 1964: The original building was 30,000 square feet. | ||
| * 2015: The building has grown to 270,000 square feet, with a third office tower and FRIB under construction | * 2015: The building has grown to 270,000 square feet, with a third office tower and FRIB under construction | ||
| - | * 2020: With conventional construction finished, the building will be 580,000 square feet. | + | * 2020: With conventional construction finished, the building is now 580,000 square feet. |
| ==== What are some good analogies to help the public relate to our work? ==== | ==== What are some good analogies to help the public relate to our work? ==== | ||
| - | A couple I've come up with lately: | ||
| * To understand how things work, sometimes you take them apart. We do the same to nuclei! | * To understand how things work, sometimes you take them apart. We do the same to nuclei! | ||
| * Many of our experiments involve "picking up the pieces" (getting detector data on various particles) and "reassembling the puzzle" (using a computer model to reconstruct the original nucleus). It's like doing a puzzle without looking at the picture on the box - more difficult, but still possible. | * Many of our experiments involve "picking up the pieces" (getting detector data on various particles) and "reassembling the puzzle" (using a computer model to reconstruct the original nucleus). It's like doing a puzzle without looking at the picture on the box - more difficult, but still possible. | ||
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| The more isotopes we discover and learn about, the better our overall picture of how the nucleus works. If you were a biologist and tried to understand living organisms in general, you wouldn't limit your research to only a few species! Note also - while those short-lived isotopes do not exist on Earth, they could be made in stellar processes and thus be key to understanding astrophysics. | The more isotopes we discover and learn about, the better our overall picture of how the nucleus works. If you were a biologist and tried to understand living organisms in general, you wouldn't limit your research to only a few species! Note also - while those short-lived isotopes do not exist on Earth, they could be made in stellar processes and thus be key to understanding astrophysics. | ||
| - | ==== What are the health risks of working with radioactive material at NSCL? ==== | + | ==== What are the health risks of working with radioactive material at FRIB? ==== |
| - | //(from Ashley Garrett)// The highest exposure to employees is for operators (300 mrem/year) who perform maintenance of the cyclotrons and target areas at NSCL. Depending on the amount of work in the cyclotrons, some end the year at 100 mrem or less. The Nuclear Regulatory Commission has estimated the loss of life expectancy due to exposure and how it compares to other potential hazards: | + | //(from Ashley Garrett)// The highest exposure to employees is for operators (300 mrem/year) who perform maintenance of the cyclotrons and target areas at FRIB. Depending on the amount of work in the cyclotrons, some end the year at 100 mrem or less. The Nuclear Regulatory Commission has estimated the loss of life expectancy due to exposure and how it compares to other potential hazards: |
| {{:tours:regulatoryguide8.29_page_09.jpg?nolink&500|}} | {{:tours:regulatoryguide8.29_page_09.jpg?nolink&500|}} | ||
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| ==== Can multiple users perform experiments simultaneously (like at SNS or other user facilities)? ==== | ==== Can multiple users perform experiments simultaneously (like at SNS or other user facilities)? ==== | ||
| - | //(from Georg Bollen, 6/20/14 Greensheet)// Providing even limited multi-user capability is desirable for NSCL and will be mandatory for FRIB. Such multi-user capability can be achieved by accessing rare isotopes that are produced but not used and presently lost on slits in the fragment separator. A promising approach is the use of a helium-jet transport system. //Also see [[https://groups.nscl.msu.edu/userinfo/greensheets/2016/The%20Greensheet3%2017%202016.pdf|3/17/16 Greensheet]]// | + | //(from Georg Bollen, 6/20/14 Greensheet)// Providing even multi-user capability is the goal for FRIB. Such multi-user capability can be achieved by accessing rare isotopes that are produced but not used and presently lost on slits in the fragment separator. A promising approach is the use of a helium-jet transport system. //Also see [[https://groups.nscl.msu.edu/userinfo/greensheets/2016/The%20Greensheet3%2017%202016.pdf|3/17/16 Greensheet]]// |
| ==== What happens to all the isotopes not used in an experiment? ==== | ==== What happens to all the isotopes not used in an experiment? ==== | ||
| - | Generally, they are trapped in the A1900 Fragment Separator and completely unused. However, //(from Georg Bollen, 11/8/13 Greensheet)// the Applied Isotope Program is exploring how to make currently unused isotopes from a beam accessible for applications such as bio-medicine, national security, energy science and material engineering. | + | Generally, they are trapped in the A1900 Fragment Separator and completely unused. However, the isotope harvesting station will make currently unused isotopes from a beam accessible for applications such as bio-medicine, national security, energy science and material engineering. |
| - | ==== Does NSCL discover superheavy (transuranium) elements? ==== | + | ==== Does FRIB discover superheavy (transuranium) elements? ==== |
| - | Our research involves the fragmentation of heavy stable isotopes to lighter and unstable isotopes, so not directly. However: //(from Zach Kohley, 6/13/14 Greensheet)// The Coincident Fission Fragment Detector (CFFD) is a new device that is currently being constructed at the NSCL for measurements of fusion-fission and quasifission reactions... [and] will guide the future experiments at FRIB aimed at the production of new neutron-rich isotopes of [superheavy elements]. | + | Our research involves the fragmentation of heavy stable isotopes to lighter and unstable isotopes, so not directly. However, we do some measurements of fusion-fission and quasifission reactions. |
| - | ==== How much did it COST to build NSCL/Cyclotrons/other equipment? ==== | + | ==== What kind of things can we learn about nuclei at FRIB? ==== |
| - | + | ||
| - | NSF commitment 2015: $23 million annual operating budget. CCF upgrade cost $20 million. MSU also funds us. Start-up costs? | + | |
| - | + | ||
| - | ==== What kind of things can we learn about nuclei at NSCL? ==== | + | |
| * Mass (and thus, binding energy) | * Mass (and thus, binding energy) | ||
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| Our research into nuclei helps explain such things as the origin/abundance of the elements, how stars explode, the nature of neutron stars, and tests of the standard model! | Our research into nuclei helps explain such things as the origin/abundance of the elements, how stars explode, the nature of neutron stars, and tests of the standard model! | ||
| - | ==== How much radiation is in the vault when the cyclotron is on? ==== | + | ==== How much radiation is in the vaults when the linac is on? ==== |
| //(from Peter Grivins)// It depends on the nuclei being accelerated. In a typical high energy beam like Oxygen-16/18, lots of neutrons can be generated. I've seen levels of at least 7+ R/hr neutron flux at a time. That means in about 1 hour, you will exceed the legal occupational limit for trained radiation workers. I'm also ignoring quality factors. So, just add up the totals: mild radiation sickness typically starts at 50 R, while certain death (LD 100/14) starts at 600-1000 R. | //(from Peter Grivins)// It depends on the nuclei being accelerated. In a typical high energy beam like Oxygen-16/18, lots of neutrons can be generated. I've seen levels of at least 7+ R/hr neutron flux at a time. That means in about 1 hour, you will exceed the legal occupational limit for trained radiation workers. I'm also ignoring quality factors. So, just add up the totals: mild radiation sickness typically starts at 50 R, while certain death (LD 100/14) starts at 600-1000 R. | ||
| - | |||
| ==== What is "LCW"? ==== | ==== What is "LCW"? ==== | ||
| - | "Low-conductivity water" is used to cool the cyclotrons. LCW reduces corrosion in copper equipment. | + | "Low-conductivity water" is used to cool some equipment. LCW reduces corrosion in copper equipment. |
| ==== What is the pressure of helium gas in the gas stoppers? ==== | ==== What is the pressure of helium gas in the gas stoppers? ==== | ||
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| (Note: these answers can still be improved upon) | (Note: these answers can still be improved upon) | ||
| - | ===== Research at NSCL ===== | + | ===== Research at FRIB ===== |
| - | ==== What research does NSCL do? ==== | + | ==== How do people get to do experiments at FRIB? ==== |
| - | [[http://www.nscl.msu.edu/science/nuggets/index.php|Some examples of recent experiments]] are on the NSCL website, or see below: | + | Scientists must send in an application proposing an experiment. An international committee reviews all proposals and awards beam time to those proposals of the highest scientific merit and greatest attainability. The average time allotted an experiment is 120 hours. In the weeks and months before the experiment, the research group and NSCL operations plan and prepare, so all the bugs are worked out before the assigned time period begins. Time not spent experimenting is time lost. When the time comes, the project runs 24 hours a day, 7 days a week. Each hour of experimentation is the reason DOE supports us, and when there’s an experiment running it costs $20,000/hr to operate FRIB. Experimenters do NOT pay to do research here. We want to maximize the amount of time the lab is available for science, about 4500 hours in most years! Experimenters spend months preparing so all the bugs are worked out before their assigned time begins. |
| - | * **From the Greensheet 10/27** To meet the demands for increased satellite performance, NASA is making more use of commercial microelectronics that tend to be prone to high-current radiation effects (e.g. single-event latchup). The more sophisticated packaging and greater complexity of state-of-the-art parts often mean that NSCL is the only practical option for single-event effects testing using high linear energy transfer irradiation. Experimenters are currently testing whether an SRAM-based FPGA with a dual Power PC core is susceptible to damage from high-energy xenon ions. It will be considered as candidate hardware for the Hubble Space Telescope if it has adequate reliability and performance. | + | ==== Who pays for people to do research at FRIB? ==== |
| - | * **From the Greensheet 10/6** The goal of Experiment 05130 (part of an ongoing LEBIT experiment) is to study further the extraction of sulfur isotopes from the gas cell and possible rare isotope molecule formation. This is in preparation for a mass measurement of 44S. The masses of this nucleus and of isotopes in its vicinity are important for a better understanding of how shell effects evolve very far away from the valley of stability. | + | The Department of Energy (DOE) Office of Science funds our operating budget, so beam time is free to researchers who are approved by the international committee. MSU contributes as well, and of course many outside users are funded by grants from NASA, NSF, etc. |
| - | + | ||
| - | * **From the Greensheet 8/11** Experiment 05043 uses the S800 and the SeGA array to study resonances of importance to the proton capture reaction that transforms 25Al into 26Si in novae explosions. This reaction is critical in the context of determining the contribution of novae to the total amount of 26Al seen in our galaxy. 26Al is an important marker of recent nucleosynthesis in the galaxy, since gamma rays from its decay in the interstellar medium have been observed with orbiting telescopes. | + | |
| - | + | ||
| - | ==== What exciting discoveries have been made HERE at NSCL? ==== | + | |
| - | + | ||
| - | According to RISAC report on 12/8/06: "Shell structure of exotic nuclei with knockout reactions", "Shell structure changes in exotic nuclei", and "78-Ni lifetime". We did pioneer the use of a superconducting cyclotron, including one for neutron therapy at Harper Hospital. We are also doing important work in the field of astrophysics, helping to explain observed astronomical phenomena by studying the nuclear processes involved. Research here is helping explain the r-process (formation of heavy elements in supernovae) and the nature of nuclear processes/explosions on neutron stars. In early 2007, we discovered the heaviest known isotope of silicon. In 2012, we observed [[https://people.nscl.msu.edu/~brown/brown-all-papers/481-2012-PhysRevLett.108.102501.pdf|dineutron decay]] for the first time. In 2016, we discovered the first instance of a [[http://www.nscl.msu.edu/news/news-23.html|"bubble nucleus" in silicon-34]]. NSCL is also the birthplace for many new technologies (such as superconducting cyclotrons, next-generation ion sources, and radiation-resistant magnets) that are spun off into other applications. | + | |
| - | + | ||
| - | + | ||
| - | ==== How do people get to do experiments at NSCL? ==== | + | |
| - | + | ||
| - | Scientists must send in an application proposing an experiment. An international committee reviews all proposals and awards beam time to those proposals of the highest scientific merit and greatest attainability. The average time alloted an experiment is 120 hours. In the weeks and months before the experiment, the research group and NSCL operations plan and prepare, so all the bugs are worked out before the assigned time period begins. Time not spent experimenting is time lost. When the time comes, the project runs 24 hours a day, 7 days a week. Each hour of experimentation is the reason NSF supports us, and when there’s an experiment running it costs $5000/hr to operate the NSCL. Experimenters do NOT pay to do research here. We want to maximize the amount of time the lab is available for science, about 4500 hours in most years! Experimenters spend months preparing so all the bugs are worked out before their assigned time begins. | + | |
| - | + | ||
| - | ==== Who pays for people to do research at NSCL? ==== | + | |
| - | + | ||
| - | The National Science Foundation funds our operating budget, so beam time is free to researchers who are approved by the international committee. MSU contributes as well, and of course many outside users are funded by grants from DOE, NASA, NSF, etc. | + | |
| ==== What are the advantages of reaccelerated beams? ==== | ==== What are the advantages of reaccelerated beams? ==== | ||
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| Our fragmentation process requires a fast beam and produces a fast beam of rare isotopes, but certain experiments can't be performed on a beam traveling half the speed of light! Many astrophysical events (such as stellar nuclear reactions) occur at a much lower energy, and so it is userful to replicate that. Reaccelerated beams also offer higher beam quality and access to many experimental techniques that were developed for low-energy beams. | Our fragmentation process requires a fast beam and produces a fast beam of rare isotopes, but certain experiments can't be performed on a beam traveling half the speed of light! Many astrophysical events (such as stellar nuclear reactions) occur at a much lower energy, and so it is userful to replicate that. Reaccelerated beams also offer higher beam quality and access to many experimental techniques that were developed for low-energy beams. | ||
| + | ==== How does research at FRIB lead to new ways to treat cancer? ==== | ||
| - | ==== What kind of experiments at NSCL would chemists be interested in? ==== | + | See [[https://frib.msu.edu/science/benefits]] on the FRIB website. |
| - | + | ||
| - | //(from Paul Mantica)// In Paul Mantica's group, the main "chemistry" connection is our NMR measurements to determine the magnetic properties of nuclei far from stability. NMR is one of the main characterization tools used by chemists; typically H-1, C-13, and P-31 are probed to look at local fields at atomic sites to determine molecular structure. Most odd-mass, stable nuclei have well-known magnetic moments, from which the unknown perturbative fields are measured (the chemical shift) and molecular structure defined. At the NSCL, we use NMR with a well known "perturbative" field to measure the unknown magnetic moments of exotic nuclei. Here, the magnetic property of the nucleus provides insight into the complicated stucture of the nuclear wavefunction. The magnetic fields we use are much smaller than those in chemistry NMR (factor of 20 or more), but since we use radioactive atoms our sensitivity for detecting the resonance condition is enhanced by 14 orders of magnitude. | + | |
| - | Dave Morrissey's groups also has a significant chemistry component. Their measurements using the gas cell are providing critically important data for the molecular formation in the gas phase. The NSCL gas cell thermalizes the fast beams for subsequent use in the LEBIT Penning Trap Mass Spectrometer. The process of stopping involves a lot of chemistry. Although many believed stopping in He buffer gas would lead directly to +1 ion formation, Dave's group has seen a complicated array of chemical reactions and different speciation depending on the chemical element involved. To date, they have studied S, As, Ge, Ga, Br, Ca among others. | + | ==== How do exploding stars make the elements and how does FRIB contribute to this research? ==== |
| - | + | ||
| - | ==== How does research at NSCL lead to new ways to treat cancer? ==== | + | |
| - | + | ||
| - | See [[http://www.nscl.msu.edu/science/applications|Medical applications of nuclear science research]] on the NSCL website. | + | |
| - | + | ||
| - | ==== How do exploding stars make the elements and how does NSCL contribute to this research? ==== | + | |
| //(from unknown source)// There is more than one type of exploding star, and each explosive scenario makes a different mix of elements and operates in a different way. The very nature of an explosion, however, gives the various scenarios some common properties. Some are faster than others, but all are fast when compared to the timescale for standard nuclear burning, such as takes place in the sun. Because the processes are fast, it becomes likely that the unstable product of one reaction will participate in another reaction before it returns to stability. In fact, large portions of key reaction sequences take place away from stability involving rare-isotopes. These processes are not yet fully understood in large part because the properties of many of these isotopes are unknown. The NSCL is one of only a few facilities in the world that can study many of the rare-isotopes important to key explosive burning processes, which produced much of the current elemental abundances, especially those of heavy elements (heavier than iron). | //(from unknown source)// There is more than one type of exploding star, and each explosive scenario makes a different mix of elements and operates in a different way. The very nature of an explosion, however, gives the various scenarios some common properties. Some are faster than others, but all are fast when compared to the timescale for standard nuclear burning, such as takes place in the sun. Because the processes are fast, it becomes likely that the unstable product of one reaction will participate in another reaction before it returns to stability. In fact, large portions of key reaction sequences take place away from stability involving rare-isotopes. These processes are not yet fully understood in large part because the properties of many of these isotopes are unknown. The NSCL is one of only a few facilities in the world that can study many of the rare-isotopes important to key explosive burning processes, which produced much of the current elemental abundances, especially those of heavy elements (heavier than iron). | ||
| * **Expanded answer** The new data will challenge descriptions of nuclei that are based on data limited to nuclei near the valley of nuclear stability. These improved models of two-component, open mesoscopic systems will contribute greatly to our understanding of mesoscopic systems in fields such as chemistry, biology and nanoscience. And more directly, the models will greatly increase our understanding of the cosmos. Today, our descriptions of stellar evolution, and especially of explosive events, such as X-ray bursts, core collapse supernovae, gamma ray bursts, thermonuclear (Type Ia) supernovae and novae, are greatly limited by inadequate knowledge of important nuclear properties. We need new data for nuclei far from stability and improved nuclear theories to develop accurate models of these astrophysical phenomena. Improved astrophysical models, in turn, will help astrophysicists make better use of data obtained from ground- and space-based observatories. They will allow us to understand the nuclear processes that produce the elements observed in the cosmos and to learn about the environments in which they were formed. For example, the abundances of the heavy r-process elements in old galactic halo stars, together with a model of the process, informed by nuclear data for very neutron-rich nuclei, allow us to constrain the entropy and neutron density near the center of a core-collapse supernova. Already today, we have the first concrete evidence that nuclear structure, well established for nuclei near the line of stability, can change dramatically as we move away from the line of stability. The effective interactions far from stability—pairing, proton-neutron, spin-orbit and tensor are different, but largely unknown. We need quantitative experimental information to refine theoretical treatments that describe these exotic isotopes. | * **Expanded answer** The new data will challenge descriptions of nuclei that are based on data limited to nuclei near the valley of nuclear stability. These improved models of two-component, open mesoscopic systems will contribute greatly to our understanding of mesoscopic systems in fields such as chemistry, biology and nanoscience. And more directly, the models will greatly increase our understanding of the cosmos. Today, our descriptions of stellar evolution, and especially of explosive events, such as X-ray bursts, core collapse supernovae, gamma ray bursts, thermonuclear (Type Ia) supernovae and novae, are greatly limited by inadequate knowledge of important nuclear properties. We need new data for nuclei far from stability and improved nuclear theories to develop accurate models of these astrophysical phenomena. Improved astrophysical models, in turn, will help astrophysicists make better use of data obtained from ground- and space-based observatories. They will allow us to understand the nuclear processes that produce the elements observed in the cosmos and to learn about the environments in which they were formed. For example, the abundances of the heavy r-process elements in old galactic halo stars, together with a model of the process, informed by nuclear data for very neutron-rich nuclei, allow us to constrain the entropy and neutron density near the center of a core-collapse supernova. Already today, we have the first concrete evidence that nuclear structure, well established for nuclei near the line of stability, can change dramatically as we move away from the line of stability. The effective interactions far from stability—pairing, proton-neutron, spin-orbit and tensor are different, but largely unknown. We need quantitative experimental information to refine theoretical treatments that describe these exotic isotopes. | ||
| - | ==== How does research at NSCL keep astronauts safe in space? ==== | + | ==== How does research at FRIB keep astronauts safe in space? ==== |
| - | Cosmic rays are much more intense in orbit and in space than they are on the surface of the earth. Standard electronic components function differently under bombardment by these high-energy particles. Your computer memory may start functioning like a particle detector. What should be a zero becomes a one after a heavy ion streams through. Components to be used in space are tested at the NSCL under the impact of individual high-energy heavy ions to make sure that astronauts can depend on them. (there may be other examples) | + | Cosmic rays are much more intense in orbit and in space than they are on the surface of the earth. Standard electronic components function differently under bombardment by these high-energy particles. Your computer memory may start functioning like a particle detector. What should be a zero becomes a one after a heavy ion streams through. Components to be used in space are tested at the FRIB under the impact of individual high-energy heavy ions to make sure that astronauts can depend on them. (there may be other examples) |
| ===== Technology ===== | ===== Technology ===== | ||
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| //(from [[http://en.wikipedia.org/wiki/Niobium|Wikipedia]])// Niobium is not found free in nature, rather as part of minerals such as columbite and pyrochlore. Brazil and Canada are the largest producers of niobium, which costs about as much as silver per ounce. Niobium is mostly used to strengthen steel, but is notable because niobium-titanium alloy remains superconducting (critical temp: 9.2K) under high current and magnetic field. Thus, the superconducting electromagnets at NSCL are made possible. (additional note: the NbTi wire costs about 5 cents per foot) | //(from [[http://en.wikipedia.org/wiki/Niobium|Wikipedia]])// Niobium is not found free in nature, rather as part of minerals such as columbite and pyrochlore. Brazil and Canada are the largest producers of niobium, which costs about as much as silver per ounce. Niobium is mostly used to strengthen steel, but is notable because niobium-titanium alloy remains superconducting (critical temp: 9.2K) under high current and magnetic field. Thus, the superconducting electromagnets at NSCL are made possible. (additional note: the NbTi wire costs about 5 cents per foot) | ||
| - | ==== Where does NSCL get the isotopes for the ion source? ==== | + | ==== Where does FRIB get the isotopes for the ion source? ==== |
| - | //(from Dallas Cole)// Many of our beams are created using monoisotopic elements or elements that are naturally very high in isotopic | + | //(from Dallas Cole)// Many of our beams are created using monoisotopic elements or elements that are naturally very high in isotopic abundance of the isotope we require, such as 238Uranium or 40Calcium. For these beams we purchase materials from common domestic chemical suppliers, such as Alfa Aesar in Massachusetts. Most of our enriched isotopes used to produce beams, such as 48Calcium or 78Krypton come from Russia through either US or Canadian distributors. The US has an inventory of these isotopes at Oak Ridge, but does not actively produce them anymore. The competitive commercial culture in Russia makes them substantially more economical in supplying our needs. Up to Calcium (Z=20) beams are produced with all electrons stripped off (totally ionized) in the liquid lithium stripper. The heaviest beam of those would be Ca-48. |
| - | abundance of the isotope we require, such as 238Uranium or 40Calcium. For these beams we purchase materials from common domestic chemical suppliers, such as Alfa Aesar in Massachusetts. Most of our enriched isotopes used to produce beams, such as 48Calcium or 78Krypton come from Russia through either US or Canadian distributors. The US has an inventory of these isotopes at Oak Ridge, but does not actively produce them anymore. The competitive commercial culture in Russia makes them substantially more economical in supplying our needs. | + | |
| - | //(from Andreas Stolz)// Up to Calcium (Z=20) beams are produced with all electrons stripped off (totally ionized) in the K1200. The heaviest beam of those would be Ca-48. //(from David Poe's cyclotron training slides)// K1200 stripper foil is of thin carbon, and the final charge state in k1200 = 2.3-2.7 times that in k500. There are 31 foils in the stripper, on a bicycle chain. | + | |
| - | + | ||
| - | + | ||
| - | ==== Why do the cyclotrons have three "dees"? ==== | + | |
| - | //(from Peter Miller)// There are three dees in our cyclotrons for a couple of reasons. | + | |
| - | + | ||
| - | 1. Mechanical fit-- With the magnet pole tip design we used, there is space in the three valleys between the hills to install dees with enough space around them to hold the operating voltage. They fit there even though the gap between the upper pole and the lower pole of the magnet is small (about 2 inches). This is essential to get the magnetic field profile we need. (We would not be able to put dees in the pole tip gap, as was done traditionally.) | + | |
| - | + | ||
| - | 2. More accelerating gaps (particles gain more energy per turn)-- The ions get an accelerating kick every time the cross the gap between the dee and the hill (2 gaps per dee). With 3 dees there are 6 accelerations on each turn. The cyclotron would work with one dee, but there would be 1/3 the energy gain per turn, so the ion would have to make three times as many turns to reach the final speed. If you could triple the voltage on that one dee you would compensate for this effect, but this is not practical. We run the dees at the highest voltage that the structure will hold reliably without much sparking. | + | |
| - | + | ||
| - | 3. Symmetrical forces on the particles -- By using 3 dees spaced symmetrically around the circle we avoid pushing the ions into an off-centered orbit when they enter the cyclotron near its center. Such errors in the centering of the orbit can damage the beam by causing it to increase in cross sectional area, even to the point where it will hit the dees and many particles will be lost before they accelerate to full speed. | + | |
| - | With only one dee, the particles would get two kicks from it (60 degrees apart on its path) and would coast all they way around (300 degrees more) before repeating the process. You can imagine how this asymmetry in the pattern of forces would tend to push the orbit off center, toward the side of the cyclotron where the dee is. | + | |
| - | + | ||
| - | In general, it is true that a dee does not have to be D-shaped to work. A D-shaped one has a width of 180 degrees. The charged particle does not experience any electic force while inside the dee; when it enters or leaves the dee it is accelerated by the electric field that is concentrated just outside the dee in the gap as it passes through it. | + | |
| - | + | ||
| - | The condition for the particle to gain maximum energy per turn is: << The particle must cross the center line of the dee just as the voltage passes through zero. >> If the particle arrives at the center line of the dee earlier or later than the zero crossing time, the energy it gains from crossing the two gaps will be less than the maximum possible. | + | |
| - | + | ||
| - | It is necessary to have the correct time synchronization between the revolving particles in the cyclotron and the oscillating voltage on the dees that produces the acceleration. In our cyclotrons the dee voltages are phased individually to be 120 degrees shifted in time, in order to match the condition for maximum energy gain. | + | |
| - | + | ||
| - | + | ||
| - | ==== What does the "K" value associated with the cyclotrons mean? ==== | + | |
| - | + | ||
| - | //(from David Poe, 10/09)// The “k” value comes from the equation E⁄A=k(〖q/A)〗^2, where E/A is in MeV/u, q is the charge state and A is the atomic mass. Labels such as k50 and k500 refer to the strongest magnetic fields we can run. For a cyclotron accelerating protons, q=A and thus q/A=1, so k is simply the energy of the protons in MeV. The k value thus represents the energy of a proton beam that could be accelerated by the same field. Note: K500 was the first single-turn extraction cyclotron, assuring a precise knowledge of the energy of particles on their exit. Note that the extraction radius of the K50 and K500 was about the same, so the switch from semiconducting to superconducting coils led to a 10x increase in beam energy! | + | |
| - | + | ||
| - | ==== What are the advantages of a cyclotron over a linear accelerator? ==== | + | |
| - | + | ||
| - | See the wiki about cyclotrons: [[http://en.wikipedia.org/wiki/Cyclotron#Advantages_of_the_Cyclotron|Advantages/Limitations of Cyclotrons]]. To summarize, the three pole tips in our cyclotrons can be used to accelerate the same nuclei again and again. This translates to a major savings in cost and space. Also, the design of the K1200/K500 compensates for relativistic effects, so they can accelerate nuclei up to a significant fraction of the speed of light (the other wiki asserts a limitation of about 1% light speed). The cyclotrons are isochronous, meaning that their magnetic fields increase with radius. //(from David Poe's cyclotron training slides)// Four magnet coils create increasing field with radius to account for relativistic mass increase (B=Bo*gamma). This actually focuses the beam in radius but defocuses it in the vertical dimension. | + | |
| ==== Then what are the advantages of linear accelerators, such as FRIB? ==== | ==== Then what are the advantages of linear accelerators, such as FRIB? ==== | ||
| They can get to higher energies by adding length, while cyclotrons are limited by their set diameter. LINACs do not require magnetic fields to constrain the particle to a circular path (which results in synchrotron radiation and loss of energy). FRIB will produce rare-isotope beams of increased intensity and variety that will ensure world-competitive research past 2030. | They can get to higher energies by adding length, while cyclotrons are limited by their set diameter. LINACs do not require magnetic fields to constrain the particle to a circular path (which results in synchrotron radiation and loss of energy). FRIB will produce rare-isotope beams of increased intensity and variety that will ensure world-competitive research past 2030. | ||
| - | |||
| - | ==== How many cyclotrons are there in the world? Where? Who is your competition? ==== | ||
| - | |||
| - | There are many cyclotrons in the world, and that number is increasing as they are built for industrial/commercial uses, such as making rare isotopes and medical treatments. The largest is the 56-foot-wide TRIUMF in Vancouver, Canada. The K1200 right here at NSCL produces the second-highest energy (up to 200 MeV/u). Our closest competitors in rare isotope research are RIKEN in Wako, Japan, which uses three cyclotrons including a recently-completed (and new highest-energy) superconducting one, and Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany, which uses a linear accelerator and synchrotron. You may know other, larger accelerators, like those at Fermilab and CERN: those are called "synchrotrons" and while they can achieve much higher energies than our facility, they are used for high-energy physics (probing the nature of individual particles, rather than a nucleus). | ||
| - | |||
| - | ==== Why couple the cyclotrons? ==== | ||
| - | |||
| - | Acceleration is dependent on the charge state of the injected nuclei. By allowing the Ion Source to produce ions with lower charge states and pre-accelerate them with the K500, we can strip MORE electrons off the faster beam nuclei and get more efficient acceleration with the K1200. The result: higher beam current AND energy. | ||
| ==== How do you "wind" a coil of superconducting wire? ==== | ==== How do you "wind" a coil of superconducting wire? ==== | ||
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| ==== How long does it take to "tune" up a rare isotope beam? ==== | ==== How long does it take to "tune" up a rare isotope beam? ==== | ||
| - | //(from Raman Anantaraman)// The minimum time has shortened significantly in recent years, down to about 12-14 hours. Having 24 hours alloted is preferable, however! | + | //(from Raman Anantaraman)// The minimum time has shortened significantly in recent years, down to about 12-14 hours. Having 24 hours allotted is preferable, however! |
| - | ==== Why choose beryllium-9 as the target? ==== | + | ==== Why choose carbon as the target? ==== |
| - | //(from Andreas Stolz)// For a fragmentation target it is good to use material with a low element number. You need nucleons for the fragmentation process, but at the same time you want to have a small electron density. Electrons in the target material would only slow down and blow up the beam, but not trigger the production of rare isotopes. Beryllium also has very good thermal properties. That means with the combination of low density, relatively high melting point, and a very good thermal conductivity the beryllium targets can be used with a high power deposition in the target without melting. Beryllium is actually the best material available under these considerations. | + | For a fragmentation target it is good to use material with a low element number. You need nucleons for the fragmentation process, but at the same time you want to have a small electron density. Electrons in the target material would only slow down and blow up the beam, but not trigger the production of rare isotopes. Carbon (graphite) also has very good thermal properties. That means with the combination of low density, relatively high melting point, and a very good thermal conductivity the carbon targets can be used with a high power deposition in the target without melting. |
| - | ==== How LONG did it take to build the NSCL/Cyclotrons/other equipment? ==== | + | ==== How LONG did it take to build FRIB to what we see today? ==== |
| * 1929: Ernest O. Lawrence invents the cyclotron. He got a patent in 1936 and Nobel Prize in 1939. | * 1929: Ernest O. Lawrence invents the cyclotron. He got a patent in 1936 and Nobel Prize in 1939. | ||
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| * 2013: ReA3 reaccelerator commissioned. | * 2013: ReA3 reaccelerator commissioned. | ||
| * 2015: ReA3 experiments begin. | * 2015: ReA3 experiments begin. | ||
| - | * 2019: Cyclotron Gas Stopper online? | + | * 2019: Cyclotron Gas Stopper online |
| - | * 2022: FRIB comes online? | + | * 2022: FRIB comes online! |
| ==== Does the A1900 Fragment Separator use the same technique as that for uranium enrichment? ==== | ==== Does the A1900 Fragment Separator use the same technique as that for uranium enrichment? ==== | ||
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| These nuclei get stopped in the beamstopper or in the magnets. | These nuclei get stopped in the beamstopper or in the magnets. | ||
| + | ==== How long does it take for a nucleus to get from the ion source to a detector? ==== | ||
| - | ==== How many nuclei are in the beam? ==== | + | Total travel time is less than one hundred microseconds, dominated by the time it takes to accelerate from the ion source through the linac. |
| - | Beam density is measured in current... that's a good description for a beam of moving positively-charged ions. Our ECR can produce varying amounts of ions, depending on the desired element. One example is a "primary beam" from the source of oxygen-16. The ECR can reliably produce 100 pnA (particle nano-amps) of this element, which equates to between 10 and 100 billion particles per second (a beam power of about 0.2 kW). Once the CCF has fragmented the primary beam and produced a filtered rare isotope beam, it represents a tiny fraction of the initial current. Beams made of isotopes near stability will contain millions of particles per second, while extremely unstable/rare isotopes could be produced at the rate of one per hour or even less! | ||
| - | ==== How long does it take for a nucleus to get from the ion source to a detector? ==== | ||
| - | Total travel time is less than one hundred microseconds, dominated by the time it takes to accelerate from the ion source through both cyclotrons. Total travel length is almost three miles. | + | ==== More information about cryogenics ==== |
| + | //(from Allyn McCartney)// The liquid helium (LHe) flows to the superconducting magnets inside | ||
| + | coaxial vacuum jacketed stainless steel pipes. There are multiple layers of | ||
| + | insulation inside the vacuum space separating the inner and outer pipes. | ||
| + | Often there is also a liquid nitrogen cooled copper shield between the 4.5 K | ||
| + | helium pipe and the 300 K outside world. The outer most vacuum jacket can | ||
| + | be either steel or stainless steel. I have several drawings that illustrate | ||
| + | some of the various schemes we use to insulate the helium pipes. When we | ||
| + | cool the stainless steel pipes they contract enough that we have to allow | ||
| + | some movement when they go back and forth between warm and cold. We use | ||
| + | flexible stainless steel hoses at times to allow for thermal contraction | ||
| + | without pulling the welds apart. | ||
| - | ==== What are some amazing facts about the cyclotrons? ==== | + | Many of our beam line magnet connections do not use stainless steel for |
| + | the helium lines. They use a special allow called Invar (also known generically as FeNi36 | ||
| + | (64FeNi in the US), is a nickel steel alloy notable for its uniquely low | ||
| + | coefficient of thermal expansion (CTE or ?))From Wikipedia. | ||
| - | Glad you asked! | + | Also we don't actually use liquid helium pumps, but push the cryogenics |
| - | - Length of superconducting wire wrapped around: | + | around the lab with pressure differentials. We run the LHe at around 11 |
| - | * K500: 20 miles | + | psig and the helium compressor inlet low pressure side is just above |
| - | * K1200: 38 miles | + | 1.5psig. |
| - | - Maximum electrical current through electromagnet: | + | |
| - | * K500: 800 amps | + | |
| - | * K1200: 1000 amps | + | |
| - | - Time a nucleus spends accelerating inside: | + | |
| - | * K500: 0.000025 seconds | + | |
| - | * K1200: 0.000035 seconds | + | |
| - | - Distance each nucleus travels inside: | + | |
| - | * K500: 0.9 miles | + | |
| - | * K1200: 1.9 miles | + | |
| - | - Number of times nuclei orbit inside: | + | |
| - | * K500: 500 (David Poe's training slides say 250) | + | |
| - | * K1200: 700 | + | |
| - | - Weight: | + | |
| - | * K500: 100 tons (3 Brontosauri) | + | |
| - | * K1200: 280 tons (8 Brontosauri) | + | |
| - | - Typical particle speed:: | + | |
| - | * K500: 30,000 mi/s | + | |
| - | * K1200: 93,000 mi/s | + | |
| + | //(from Raman Anantaraman)// The lab's annual liquid helium budget is over $300,000. | ||
| + | |||
| + | ==== How many square feet is the FRIB building? ==== | ||
| + | |||
| + | Currently the facility is over 500,000 square feet. The SRF high bay and the FRIB project doubled our space! | ||
| + | |||
| + | ==== Where were the S800 Dipoles built? ==== | ||
| + | |||
| + | //(from Al Zeller)// The steel came from Japan, the conductor from Italy and the coil bobbins from Colorado. Everything else was procured locally. The complete dipoles were built here in the S3 pit and the East High Bay. | ||
| + | |||
| + | ===== Introduction (demos, education, other) ===== | ||
| + | |||
| + | ==== How dangerous are the radioactive plate (Fiestaware) and lantern mantle? ==== | ||
| + | |||
| + | Read up on [[http://www.orau.org/ptp/collection/consumer%20products/fiesta.htm|Fiestaware]] and [[http://www.orau.org/ptp/collection/consumer%20products/mantle.htm|lantern mantles]] at the Oak Ridge website. However, the pertinent exposure data are: | ||
| + | * Fiestaware: "Although the uranium in the glaze emits gamma rays, alpha particles, and beta particles, the gamma and alpha emissions are weak. The beta particles are the easiest to detect, and they are also responsible for the bulk of the radiation exposure to those handling ceramics that employ a uranium glaze." "NUREG-1717 estimated that an individual using nothing but this type of dinnerware might consume 0.21 grams of uranium per year... [and] might have an effective dose equivalent of 40 mrem per year. This was the highest dose calculated in any of the exposure pathways considered by NUREG-1717." | ||
| + | * Lantern mantles: Thorium and many of its daughter products are alpha emitters. "Avid campers were estimated to receive 0.05 to 6 mrem per year, while the estimate for one-time campers was 0.002 to 0.06 mrem." | ||
| + | |||
| + | ==== Is FRIB a good place to come for graduate school? ==== | ||
| + | |||
| + | Thanks to FRIB, MSU's nuclear physics program is ranked number two in the nation (traded places with MIT) by US News & World Report in its 2022 issue of [[http://www.usnews.com/usnews/edu/grad/rankings/phdsci/brief/physp5_brief.php|America's Best Graduate Schools]]. FRIB currently educates about 10% of the nation's PhD students in nuclear science (physics and chemistry). We also educate and employ many undergraduates. | ||
| + | |||
| + | ==== What is the ceramic superconductor in the petri dish made of? ==== | ||
| + | |||
| + | It is a YBCO superconductor, standing for Yttrium Barium Copper Oxide. This ceramic becomes superconducting at about 92K, which means that LN (77K) is sufficient to cool it. More info at the [[http://en.wikipedia.org/wiki/YBCO|Wikipedia YBCO article]]. You can find [[http://superconductors.org/Play.htm|places to buy YBCO superconductors]]. | ||
| + | |||
| + | ==== How much does liquid nitrogen cost? Where do you get it? ==== | ||
| + | |||
| + | //(from Helmut Laumer)// The present contract is $0.26/gal of liquid nitrogen and $9.4/gal of liquid helium. The production power cost for liquid nitrogen (which is available free from the air) is half the price; hence not cost effective to produce our own. The reliquefaction power cost for liquid helium is about $0.25/gallon, hence that is cost effective and we only buy gas to cover our losses. We get both from a chemical supplier. | ||
| + | |||
| + | {{ :tours:discussion:mlev.gif}}{{ :tours:discussion:cblv.jpg}} | ||
| + | ==== Why do magnets float over a superconductor? ==== | ||
| + | |||
| + | The Meissner effect in superconductors like this black ceramic yttrium based superconductor acts to exclude magnetic fields from the material. Since the electrical resistance is zero, supercurrents are generated in the material to exclude the magnetic fields from a magnet brought near it. The currents which cancel the external field produce magnetic poles which mirror the poles of the permanent magnet, repelling them to provide the lift to levitate the magnet. The levitation process is quite remarkable. Since the levitating currents in the superconductor meet no resistance, they can adjust almost instantly to maintain the levitation. The suspended magnet can be moved, put into oscillation, or even spun rapidly and the levitation currents will adjust to keep it in suspension. | ||
| + | |||
| + | ==== What was the last "lost-time accident" at FRIB/NSCL? ==== | ||
| + | |||
| + | //(from Terry Monahan)// Someone slipped on some ice in the parking lot and was hurt. They missed one day of work. It occurred around 2001. | ||
| + | |||
| + | ===== Old NSCL FAQ ===== | ||
| + | |||
| + | ==== How strong are the (neodymium) magnets floating over the superconductor compared to the magnets in the cyclotron? ==== | ||
| + | |||
| + | The cyclotrons produce 3-5 Tesla over a fairly large area. The floating magnet is Neodymium, a powerful rare-earth magnet. Even so, as an N35-grade magnet (a classification of power for Nd magnets), you would probably measure 0.25 Tesla about 1/16" away from its surface. The Earth's magnetic field is 0.00005 Tesla; our cyclotrons are about 100,000 times stronger. | ||
| ==== More Information about operating the cyclotron ==== | ==== More Information about operating the cyclotron ==== | ||
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| The steel shell around the cyclotron is called the "yoke" and serves to propagate the magnetic field, making it as strong as possible. | The steel shell around the cyclotron is called the "yoke" and serves to propagate the magnetic field, making it as strong as possible. | ||
| - | ==== More information about cryogenics ==== | + | ==== What are some amazing facts about the cyclotrons? ==== |
| - | //(from Allyn McCartney)// The liquid helium (LHe) flows to the superconducting magnets inside | + | |
| - | coaxial vacuum jacketed stainless steel pipes. There are multiple layers of | + | |
| - | insulation inside the vacuum space separating the inner and outer pipes. | + | |
| - | Often there is also a liquid nitrogen cooled copper shield between the 4.5 K | + | |
| - | helium pipe and the 300 K outside world. The outer most vacuum jacket can | + | |
| - | be either steel or stainless steel. I have several drawings that illustrate | + | |
| - | some of the various schemes we use to insulate the helium pipes. When we | + | |
| - | cool the stainless steel pipes they contract enough that we have to allow | + | |
| - | some movement when they go back and forth between warm and cold. We use | + | |
| - | flexible stainless steel hoses at times to allow for thermal contraction | + | |
| - | without pulling the welds apart. | + | |
| - | Many of our beam line magnet connections do not use stainless steel for | + | Glad you asked! |
| - | the helium lines. They use a special allow called Invar (also known generically as FeNi36 | + | - Length of superconducting wire wrapped around: |
| - | (64FeNi in the US), is a nickel steel alloy notable for its uniquely low | + | * K500: 20 miles |
| - | coefficient of thermal expansion (CTE or ?))From Wikipedia. | + | * K1200: 38 miles |
| + | - Maximum electrical current through electromagnet: | ||
| + | * K500: 800 amps | ||
| + | * K1200: 1000 amps | ||
| + | - Time a nucleus spends accelerating inside: | ||
| + | * K500: 0.000025 seconds | ||
| + | * K1200: 0.000035 seconds | ||
| + | - Distance each nucleus travels inside: | ||
| + | * K500: 0.9 miles | ||
| + | * K1200: 1.9 miles | ||
| + | - Number of times nuclei orbit inside: | ||
| + | * K500: 500 (David Poe's training slides say 250) | ||
| + | * K1200: 700 | ||
| + | - Weight: | ||
| + | * K500: 100 tons (3 Brontosauri) | ||
| + | * K1200: 280 tons (8 Brontosauri) | ||
| + | - Typical particle speed:: | ||
| + | * K500: 30,000 mi/s | ||
| + | * K1200: 93,000 mi/s | ||
| - | Also we don't actually use liquid helium pumps, but push the cryogenics | + | ==== How many nuclei are in the beam? ==== |
| - | around the lab with pressure differentials. We run the LHe at around 11 | + | |
| - | psig and the helium compressor inlet low pressure side is just above | + | |
| - | 1.5psig. | + | |
| - | //(from Raman Anantaraman)// The lab's annual liquid helium budget is over $300,000. | + | Beam density is measured in current... that's a good description for a beam of moving positively-charged ions. Our ECR can produce varying amounts of ions, depending on the desired element. One example is a "primary beam" from the source of oxygen-16. The ECR can reliably produce 100 pnA (particle nano-amps) of this element, which equates to between 10 and 100 billion particles per second (a beam power of about 0.2 kW). Once the CCF has fragmented the primary beam and produced a filtered rare isotope beam, it represents a tiny fraction of the initial current. Beams made of isotopes near stability will contain millions of particles per second, while extremely unstable/rare isotopes could be produced at the rate of one per hour or even less! |
| - | ==== How many square feet is the NSCL building? ==== | + | ==== Why couple the cyclotrons? ==== |
| - | //(from Paul Zeller, 9/13)// Currently the facility is recorded at 235,963 square feet. The SRF high bay and the FRIB project will approximately double that number. I tell people we are about a quarter million square feet, and after FRIB is constructed we will be about half a million square feet. | + | Acceleration is dependent on the charge state of the injected nuclei. By allowing the Ion Source to produce ions with lower charge states and pre-accelerate them with the K500, we can strip MORE electrons off the faster beam nuclei and get more efficient acceleration with the K1200. The result: higher beam current AND energy. |
| - | ==== Where were the S800 Dipoles built? ==== | + | ==== How many cyclotrons are there in the world? Where? Who is your competition? ==== |
| - | //(from Al Zeller)// The steel came from Japan, the conductor from Italy and the coil bobbins from Colorado. Everything else was procured locally. The complete dipoles were built here in the S3 pit and the East High Bay. | + | There are many cyclotrons in the world, and that number is increasing as they are built for industrial/commercial uses, such as making rare isotopes and medical treatments. The largest is the 56-foot-wide TRIUMF in Vancouver, Canada. The K1200 right here at NSCL produces the second-highest energy (up to 200 MeV/u). Our closest competitors in rare isotope research are RIKEN in Wako, Japan, which uses three cyclotrons including a recently-completed (and new highest-energy) superconducting one, and Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany, which uses a linear accelerator and synchrotron. You may know other, larger accelerators, like those at Fermilab and CERN: those are called "synchrotrons" and while they can achieve much higher energies than our facility, they are used for high-energy physics (probing the nature of individual particles, rather than a nucleus). |
| - | ===== Introduction (demos, education, other) ===== | + | ==== What are the advantages of a cyclotron over a linear accelerator? ==== |
| - | ==== How dangerous are the radioactive plate (Fiestaware) and lantern mantle? ==== | + | See the wiki about cyclotrons: [[http://en.wikipedia.org/wiki/Cyclotron#Advantages_of_the_Cyclotron|Advantages/Limitations of Cyclotrons]]. To summarize, the three pole tips in our cyclotrons can be used to accelerate the same nuclei again and again. This translates to a major savings in cost and space. Also, the design of the K1200/K500 compensates for relativistic effects, so they can accelerate nuclei up to a significant fraction of the speed of light (the other wiki asserts a limitation of about 1% light speed). The cyclotrons are isochronous, meaning that their magnetic fields increase with radius. //(from David Poe's cyclotron training slides)// Four magnet coils create increasing field with radius to account for relativistic mass increase (B=Bo*gamma). This actually focuses the beam in radius but defocuses it in the vertical dimension. |
| - | Read up on [[http://www.orau.org/ptp/collection/consumer%20products/fiesta.htm|Fiestaware]] and [[http://www.orau.org/ptp/collection/consumer%20products/mantle.htm|lantern mantles]] at the Oak Ridge website. However, the pertinent exposure data are: | + | ==== Why do the cyclotrons have three "dees"? ==== |
| - | * Fiestaware: "Although the uranium in the glaze emits gamma rays, alpha particles, and beta particles, the gamma and alpha emissions are weak. The beta particles are the easiest to detect, and they are also responsible for the bulk of the radiation exposure to those handling ceramics that employ a uranium glaze." "NUREG-1717 estimated that an individual using nothing but this type of dinnerware might consume 0.21 grams of uranium per year... [and] might have an effective dose equivalent of 40 mrem per year. This was the highest dose calculated in any of the exposure pathways considered by NUREG-1717." | + | //(from Peter Miller)// There are three dees in our cyclotrons for a couple of reasons. |
| - | * Lantern mantles: Thorium and many of its daughter products are alpha emitters. "Avid campers were estimated to receive 0.05 to 6 mrem per year, while the estimate for one-time campers was 0.002 to 0.06 mrem." | + | |
| - | ==== Is NSCL a good place to come for graduate school? ==== | + | 1. Mechanical fit-- With the magnet pole tip design we used, there is space in the three valleys between the hills to install dees with enough space around them to hold the operating voltage. They fit there even though the gap between the upper pole and the lower pole of the magnet is small (about 2 inches). This is essential to get the magnetic field profile we need. (We would not be able to put dees in the pole tip gap, as was done traditionally.) |
| - | Thanks to the NSCL, MSU's nuclear physics program is ranked number one in the nation (now ahead of MIT) by US News & World Report in its 2010 issue of [[http://www.usnews.com/usnews/edu/grad/rankings/phdsci/brief/physp5_brief.php|America's Best Graduate Schools]]. NSCL currently educates about 10% of the nation's PhD students in nuclear science (physics and chemistry). We also educate and employ many undergraduates. | + | 2. More accelerating gaps (particles gain more energy per turn)-- The ions get an accelerating kick every time the cross the gap between the dee and the hill (2 gaps per dee). With 3 dees there are 6 accelerations on each turn. The cyclotron would work with one dee, but there would be 1/3 the energy gain per turn, so the ion would have to make three times as many turns to reach the final speed. If you could triple the voltage on that one dee you would compensate for this effect, but this is not practical. We run the dees at the highest voltage that the structure will hold reliably without much sparking. |
| - | ==== What is the difference between the dark/light green walls shown on the map in the seminar room? ==== | + | 3. Symmetrical forces on the particles -- By using 3 dees spaced symmetrically around the circle we avoid pushing the ions into an off-centered orbit when they enter the cyclotron near its center. Such errors in the centering of the orbit can damage the beam by causing it to increase in cross sectional area, even to the point where it will hit the dees and many particles will be lost before they accelerate to full speed. |
| + | With only one dee, the particles would get two kicks from it (60 degrees apart on its path) and would coast all they way around (300 degrees more) before repeating the process. You can imagine how this asymmetry in the pattern of forces would tend to push the orbit off center, toward the side of the cyclotron where the dee is. | ||
| - | Dark green = poured concrete, permanent. Light green = stacked concrete blocks, movable. We're also getting in some large, shaped "Morris" blocks for the rebuilt walls in this summer's reconstruction. | + | In general, it is true that a dee does not have to be D-shaped to work. A D-shaped one has a width of 180 degrees. The charged particle does not experience any electic force while inside the dee; when it enters or leaves the dee it is accelerated by the electric field that is concentrated just outside the dee in the gap as it passes through it. |
| - | ==== How strong are the (neodymium) magnets floating over the superconductor compared to the magnets in the cyclotron? ==== | + | The condition for the particle to gain maximum energy per turn is: << The particle must cross the center line of the dee just as the voltage passes through zero. >> If the particle arrives at the center line of the dee earlier or later than the zero crossing time, the energy it gains from crossing the two gaps will be less than the maximum possible. |
| - | The cyclotrons produce 3-5 Tesla over a fairly large area. The floating magnet is Neodymium, a powerful rare-earth magnet. Even so, as an N35-grade magnet (a classification of power for Nd magnets), you would probably measure 0.25 Tesla about 1/16" away from its surface. The Earth's magnetic field is 0.00005 Tesla; our cyclotrons are about 100,000 times stronger. | + | It is necessary to have the correct time synchronization between the revolving particles in the cyclotron and the oscillating voltage on the dees that produces the acceleration. In our cyclotrons the dee voltages are phased individually to be 120 degrees shifted in time, in order to match the condition for maximum energy gain. |
| - | ==== What is the ceramic superconductor in the petri dish made of? ==== | ||
| - | It is a YBCO superconductor, standing for Yttrium Barium Copper Oxide. This ceramic becomes superconducting at about 92K, which means that LN (77K) is sufficient to cool it. More info at the [[http://en.wikipedia.org/wiki/YBCO|Wikipedia YBCO article]]. You can find [[http://superconductors.org/Play.htm|places to buy YBCO superconductors]]. | + | ==== What does the "K" value associated with the cyclotrons mean? ==== |
| - | ==== How much does liquid nitrogen cost? Where do you get it? ==== | + | //(from David Poe, 10/09)// The “k” value comes from the equation E⁄A=k(〖q/A)〗^2, where E/A is in MeV/u, q is the charge state and A is the atomic mass. Labels such as k50 and k500 refer to the strongest magnetic fields we can run. For a cyclotron accelerating protons, q=A and thus q/A=1, so k is simply the energy of the protons in MeV. The k value thus represents the energy of a proton beam that could be accelerated by the same field. Note: K500 was the first single-turn extraction cyclotron, assuring a precise knowledge of the energy of particles on their exit. Note that the extraction radius of the K50 and K500 was about the same, so the switch from semiconducting to superconducting coils led to a 10x increase in beam energy! |
| - | //(from Helmut Laumer)// The present contract is $0.26/gal of liquid nitrogen and $9.4/gal of liquid helium. The production power cost for liquid nitrogen (which is available free from the air) is half the price; hence not cost effective to produce our own. The reliquefaction power cost for liquid helium is about $0.25/gallon, hence that is cost effective and we only buy gas to cover our losses. We get both from a chemical supplier. | + | ==== What kind of experiments at NSCL would chemists be interested in? ==== |
| + | |||
| + | //(from Paul Mantica)// In Paul Mantica's group, the main "chemistry" connection is our NMR measurements to determine the magnetic properties of nuclei far from stability. NMR is one of the main characterization tools used by chemists; typically H-1, C-13, and P-31 are probed to look at local fields at atomic sites to determine molecular structure. Most odd-mass, stable nuclei have well-known magnetic moments, from which the unknown perturbative fields are measured (the chemical shift) and molecular structure defined. At the NSCL, we use NMR with a well known "perturbative" field to measure the unknown magnetic moments of exotic nuclei. Here, the magnetic property of the nucleus provides insight into the complicated stucture of the nuclear wavefunction. The magnetic fields we use are much smaller than those in chemistry NMR (factor of 20 or more), but since we use radioactive atoms our sensitivity for detecting the resonance condition is enhanced by 14 orders of magnitude. | ||
| - | {{ :tours:discussion:mlev.gif}}{{ :tours:discussion:cblv.jpg}} | + | Dave Morrissey's groups also has a significant chemistry component. Their measurements using the gas cell are providing critically important data for the molecular formation in the gas phase. The NSCL gas cell thermalizes the fast beams for subsequent use in the LEBIT Penning Trap Mass Spectrometer. The process of stopping involves a lot of chemistry. Although many believed stopping in He buffer gas would lead directly to +1 ion formation, Dave's group has seen a complicated array of chemical reactions and different speciation depending on the chemical element involved. To date, they have studied S, As, Ge, Ga, Br, Ca among others. |
| - | ==== Why do magnets float over a superconductor? ==== | + | |
| - | The Meissner effect in superconductors like this black ceramic yttrium based superconductor acts to exclude magnetic fields from the material. Since the electrical resistance is zero, supercurrents are generated in the material to exclude the magnetic fields from a magnet brought near it. The currents which cancel the external field produce magnetic poles which mirror the poles of the permanent magnet, repelling them to provide the lift to levitate the magnet. The levitation process is quite remarkable. Since the levitating currents in the superconductor meet no resistance, they can adjust almost instantly to maintain the levitation. The suspended magnet can be moved, put into oscillation, or even spun rapidly and the levitation currents will adjust to keep it in suspension. | + | ==== What exciting discoveries have been made HERE at NSCL? ==== |
| - | ==== What was the last "lost-time accident" at NSCL? ==== | + | According to RISAC report on 12/8/06: "Shell structure of exotic nuclei with knockout reactions", "Shell structure changes in exotic nuclei", and "78-Ni lifetime". We did pioneer the use of a superconducting cyclotron, including one for neutron therapy at Harper Hospital. We are also doing important work in the field of astrophysics, helping to explain observed astronomical phenomena by studying the nuclear processes involved. Research here is helping explain the r-process (formation of heavy elements in supernovae) and the nature of nuclear processes/explosions on neutron stars. In early 2007, we discovered the heaviest known isotope of silicon. In 2012, we observed [[https://people.nscl.msu.edu/~brown/brown-all-papers/481-2012-PhysRevLett.108.102501.pdf|dineutron decay]] for the first time. In 2016, we discovered the first instance of a [[http://www.nscl.msu.edu/news/news-23.html|"bubble nucleus" in silicon-34]]. NSCL is also the birthplace for many new technologies (such as superconducting cyclotrons, next-generation ion sources, and radiation-resistant magnets) that are spun off into other applications. |
| + | |||
| + | ==== What research does NSCL do? ==== | ||
| + | |||
| + | [[http://www.nscl.msu.edu/science/nuggets/index.php|Some examples of recent experiments]] are on the NSCL website, or see below: | ||
| + | |||
| + | * **From the Greensheet 10/27** To meet the demands for increased satellite performance, NASA is making more use of commercial microelectronics that tend to be prone to high-current radiation effects (e.g. single-event latchup). The more sophisticated packaging and greater complexity of state-of-the-art parts often mean that NSCL is the only practical option for single-event effects testing using high linear energy transfer irradiation. Experimenters are currently testing whether an SRAM-based FPGA with a dual Power PC core is susceptible to damage from high-energy xenon ions. It will be considered as candidate hardware for the Hubble Space Telescope if it has adequate reliability and performance. | ||
| + | |||
| + | * **From the Greensheet 10/6** The goal of Experiment 05130 (part of an ongoing LEBIT experiment) is to study further the extraction of sulfur isotopes from the gas cell and possible rare isotope molecule formation. This is in preparation for a mass measurement of 44S. The masses of this nucleus and of isotopes in its vicinity are important for a better understanding of how shell effects evolve very far away from the valley of stability. | ||
| + | |||
| + | * **From the Greensheet 8/11** Experiment 05043 uses the S800 and the SeGA array to study resonances of importance to the proton capture reaction that transforms 25Al into 26Si in novae explosions. This reaction is critical in the context of determining the contribution of novae to the total amount of 26Al seen in our galaxy. 26Al is an important marker of recent nucleosynthesis in the galaxy, since gamma rays from its decay in the interstellar medium have been observed with orbiting telescopes. | ||
| + | |||
| + | ==== What is the heaviest rare isotope beam ever studied at NSCL? ==== | ||
| + | Tellurium-134. | ||
| + | |||
| + | ==== What kind of controls are used? ==== | ||
| + | //(From the NSCL website)// EPICS - Experimental Physics and Industrial Control System is a distributed control system that was written jointly by LosAlamos an Argonne National Laboratories. It is also the control system used to control and monitor the NSCL Control system and beamlines. The NSCL data acquisition system has a certain level of support for accessing EPICS. This support gets built if the EPICS base software can be located at configuration time when the NSCL DAQ software is built and installed. Please note that the NSCL data acquisition group has also written a more complete EPICS access package, with Tcl/Tk EPICS aware widgets that is distributed seperately. That software is tested on Linux, Windows as well as MAC OS-X. | ||
| - | //(from Terry Monahan)// Someone slipped on some ice in the parking lot and was hurt. They missed one day of work. It occurred around 2001. | ||
tours/faq.1552940107.txt.gz · Last modified: 2019/03/18 16:15 by constan
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