baboons
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| - | This is the project page for BaBooNs. | + | **This is the project page for BaBooNs. ** |
| + | Kaitlin Cook: Parameters | ||
| + | Justin Michael Brown: Code | ||
| + | Rob Almus: Analysis | ||
| + | |||
| + | **Aim**: Investigate the effects of non-thermal baryon injection on BBN. | ||
| + | |||
| + | **Introduction** | ||
| + | If dark matter particles (e.g. WIMPS) exist, they inevitably did so during the big bang. They also may decay during BBN into non-thermal particles - this may be in the form of photons, leptons (electron/positron pairs and/or neutrinos) or into hadronic channels (n/p, mesons, nuclei). These decays may have two influences into BBN: | ||
| + | |||
| + | 1) Change the expansion rate due to the injection of relativistic species. | ||
| + | |||
| + | 2) Effect the abundance of light nuclei produced in BBN via reactions with these decay particles. | ||
| + | |||
| + | In case (1), this effect is important only if the decay channels are relativistic, thus adding a lot of entropy into the universe. In this project, we will consider the injection of neutrons, so we will not consider this effect. | ||
| + | |||
| + | It is thus the goal of this project to investigate the effect of the injection of non-thermal neutrons on the light element abundances. | ||
| + | |||
| + | **Key parameters: ** | ||
| + | |||
| + | - The mean life of the decaying particle X -> 2n (some magic decay. Not very physical, probably. But hey, we don't actually know what WIMPS are). | ||
| + | - The energy of these neutrons (although if it is high enough, it may not matter too much?) | ||
| + | - The abundance of X. Jedamzik, 2004: 7Be is suppressed if O(10^-5) neutrons per proton are injected. Increases D/H. Lifetime of ~1000 s required. | ||
| + | - n interaction rates with every other nucleus. | ||
| + | - Mass of the WIMP. Chosen to be 100 GeV, based on the wikipedia WIMP entry, the font of all wisdom. | ||
| + | |||
| + | This figure: | ||
| + | |||
| + | {{::cdms_parameter_space_2004.png?600|}} | ||
| + | |||
| + | from CDMS in 2004 suggests that this value isn't too far off. | ||
| + | |||
| + | **Code: ** | ||
| + | |||
| + | - **How to add an Isotope to bigbang** | ||
| + | - Add pointer identifier, id, in network.dek (e.g. ini56) | ||
| + | - In subroutine init_bigbang: | ||
| + | - Add 1 to ionmax | ||
| + | - Set id number (usually +1 of the last isotope) | ||
| + | - id = number | ||
| + | - Set ratnam (name e.g. "ni56") | ||
| + | - ionam (id) = isotope name | ||
| + | - Set zion (# of protons) | ||
| + | - zion (id) = Z | ||
| + | - Set aion (mass number) | ||
| + | - aion (id) = A | ||
| + | - Set bion (binding energy) | ||
| + | - bion (id) = binding energy | ||
| + | - In net_input | ||
| + | - Add initial abundance in xin | ||
| + | - xin (id) | ||
| + | - In init_isotope_rate_pointers | ||
| + | - Set pointer to 0 | ||
| + | - id = 0 | ||
| + | - **How to add a Reaction Rate to bigbang** | ||
| + | - Add reaction subroutine | ||
| + | - Add reaction and reverse reaction pointers, irid and irrid, in network.dek | ||
| + | - In subroutine init_bigbang: | ||
| + | - Add 2 to nrat | ||
| + | - Set id numbers, usually +1 of last reaction | ||
| + | - irid = number | ||
| + | - irrid = number + 1 | ||
| + | - Set names | ||
| + | - ratnam (irid) = reaction name | ||
| + | - ratnam (irrid) = reverse reaction name | ||
| + | - In subroutine init_isotope_rate_pointers | ||
| + | - Set pointers to 0 | ||
| + | - irid = 0 | ||
| + | - irrid = 0 | ||
| + | - In subroutine bigbangrat | ||
| + | - Call reaction subroutine | ||
| + | - call rate_id (btemp,bden,ratraw(irid),dratrawdt(irid),dratrawdd(irid),ratraw(irrid),dratrawdt(irrid),dratrawdd(irrid) | ||
| + | - Arguments | ||
| + | - temp => temperature in K | ||
| + | - den => density in g/cm^3 | ||
| + | - fr => forward reaction rate, N_a<sigma v> | ||
| + | - dfrdt => derivative of fr with respect to temp | ||
| + | - dfrdd => derivative of fr with respect to den | ||
| + | - rr => reverse reaction rate, N_a<sigma v> | ||
| + | - drrdt => derivative of fr with respect to temp | ||
| + | - drrdd => derivative of fr with respect to den | ||
| + | - In subroutine bigbangtab | ||
| + | - Add density dependence | ||
| + | - dtab(irid) = 1.0d0 for decay | ||
| + | - dtab(irid) = bden for 2-body interaction | ||
| + | - Likewise for irrid | ||
| + | - In subroutine rhs: | ||
| + | - Add dy/dt terms | ||
| + | - dydt(isotope1) = dydt(isotope1) - y(isotope1) * y(isotope2) * rate(irid) | ||
| + | - dydt(isotope2) = dydt(isotope2) - y(isotope1) * y(isotope2) * rate(irid) | ||
| + | - dydt(output) = dydt(output) + y(isotope1) * y(isotope2) * rate(irid) | ||
| + | - Likewise for reverse reaction | ||
| + | - In subroutine bbigbang | ||
| + | - Add tree calls for reaction if they don't exist | ||
| + | - call tree(isotope1,isotope1,eloc,neloc,nterms,nzo,iloc,jloc,np) | ||
| + | - call tree(isotope1,isotope2,eloc,neloc,nterms,nzo,iloc,jloc,np) | ||
| + | - call tree(isotope2,isotope1,eloc,neloc,nterms,nzo,iloc,jloc,np) | ||
| + | - call tree(isotope2,isotope2,eloc,neloc,nterms,nzo,iloc,jloc,np) | ||
| + | - call tree(output,isotope1,eloc,neloc,nterms,nzo,iloc,jloc,np) | ||
| + | - call tree(output,isotope2,eloc,neloc,nterms,nzo,iloc,jloc,np) | ||
| + | - In subroutine sbigbang | ||
| + | - Add Jacobian elements | ||
| + | - For example, for d(isotope1)/d(isotope2) | ||
| + | - a1 = -y(isotope1)*ratdum(irid) | ||
| + | - nt = nt + 1, only if this Jacobian element doesn't already exist | ||
| + | - iat = eloc(nt), only if this Jacobian element doesn't already exist | ||
| + | - dfdy(iat) = dydy(iat) + a1 | ||
| + | - xsum(isotope2) = xsum(isotope2) + a1 * mion(isotope1) | ||
| + | - Likewise for d(isotope1)/d(isotope1), d(isotope2)/d(isotope1), etc. | ||
| + | - For example, for d(output)/d(isotope2) | ||
| + | - a1 = -y(isotope1)*ratdum(irid) | ||
| + | - nt = nt + 1, only if this Jacobian element doesn't already exist | ||
| + | - iat = eloc(nt), only if this Jacobian element doesn't already exist | ||
| + | - dfdy(iat) = dydy(iat) + a1 | ||
| + | - xsum(isotope2) = xsum(isotope2) + a1 * mion(output) | ||
| + | - Likewise for d(output)/d(isotope1) | ||
| + | - Do likewise for the reverse reaction rate, making sure not to repeat any of the above lines that shouldn't be done if the element already exists | ||
| + | |||
| + | |||
| + | |||
| + | |||
| + | Reference Papers: | ||
| + | |||
| + | Cyburt et. al. 2009. Nucleosynthesis Constraints on a Massive Gravitino in Neutralino Dark Matter Scenario [[http://arxiv.org/pdf/0907.5003v1.pdf]] | ||
| + | |||
| + | |||
| + | Kamionkowski 1994. Diffuse Gamma Rays from WIMP Decay and Annihilation [[http://arxiv.org/pdf/astro-ph/9404079v1.pdf]] | ||
| + | |||
| + | Pierre Salati, 2014. Dark Matter Annihilation in the Universe [[http://arxiv.org/pdf/1403.4495.pdf]] | ||
| + | |||
| + | **Logbook** | ||
baboons.txt ยท Last modified: 2014/06/13 10:24 by cook
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