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detectors [2013/12/13 19:14]
pereira [Cathode Readout Drift Chambers (CRDC)] |
detectors [2013/12/20 15:02]
pereira [Plastic scintillators] |
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| ===== Plastic scintillators ===== | ===== Plastic scintillators ===== |
| In order to determine the Time-Of-Flight for the particle identification, the S800 includes a plastic scintillator at the [[Stations#Object |object station]] (S800_OBJ) and at the [[Stations|focal-plane station]] (E1). The detector material typically used is | In order to determine the Time-Of-Flight for the particle identification, the S800 includes a plastic scintillator at the [[Stations#Object|object station]] (S800_OBJ) and at the [[Stations|focal-plane station]] (E1). The detector material typically used is |
| [[http://www.detectors.saint-gobain.com/uploadedFiles/SGdetectors/Documents/Product_Data_Sheets/BC400-404-408-412-416-Data-Sheet.pdf|BC-400]] or [[http://www.detectors.saint-gobain.com/uploadedFiles/SGdetectors/Documents/Product_Data_Sheets/BC400-404-408-412-416-Data-Sheet.pdf|BC-404]] made from polyvinyltoluene (>97% ) and organic fluors (<3%) with a density 1.032 g/cm<sup>3</sup> and a refractive index 1.58. The thickness of the detectors is chosen on the basis of the charge of the nuclei to be measured. The available thicknesses are __127 μm and 1 mm__ for OBJ_SCI and __xxxxxx__ for E1. The OBJ_SCI has an active area of __xxx__ and is connected to a photomultiplier __xxx__. The E1 scintillator is read out at each end with an [[EMI 98807B]] photomultiplier, allowing for mean timing. Different Time-Of-Flights can be constructed by combining the timing signals from these two detectors with the timing signals from the [[https://groups.nscl.msu.edu/a1900/|A1900]] focal plane, and the RF cyclotron. The E1 detector is also used to define a valid trigger from the S800. The timing resolution for a point-like beam spot in the focal plane is around 100 ps. However, this resolution worsens significantly (up to 1 ns) when the whole focal plane is illuminated, because of path length differences of the traversing nuclei. It can be recovered by tracking the position of each event on the scintillator from the position and angle information provided by the [[Detectors#Cathode Readout Drift Chambers (CRDC)|CRDC]] detectors. The plastic scintillators can withstand maximum rates up to 1 x 10<sup>6</sup> particles per second. | [[http://www.detectors.saint-gobain.com/uploadedFiles/SGdetectors/Documents/Product_Data_Sheets/BC400-404-408-412-416-Data-Sheet.pdf|BC-400]] or [[http://www.detectors.saint-gobain.com/uploadedFiles/SGdetectors/Documents/Product_Data_Sheets/BC400-404-408-412-416-Data-Sheet.pdf|BC-404]] made from polyvinyltoluene (>97% ) and organic fluors (<3%) with a density 1.032 g/cm<sup>3</sup> and a refractive index 1.58. The thickness of the detectors is chosen on the basis of the charge of the nuclei to be measured. The available thicknesses are __127 μm and 1 mm__ for OBJ_SCI and __1 mm and 5 mm__ for E1. The OBJ_SCI has an active area of __xxx__ and is connected to a photomultiplier __xxx__. The E1 scintillator is read out at each end with an [[EMI 98807B]] photomultiplier, allowing for mean timing. Different Time-Of-Flights can be constructed by combining the timing signals from these two detectors with the timing signals from the [[https://groups.nscl.msu.edu/a1900/|A1900]] focal plane, and the RF cyclotron. The E1 detector is also used to define a valid trigger from the S800. The timing resolution for a point-like beam spot in the focal plane is around 100 ps. However, this resolution worsens significantly (up to 1 ns) when the whole focal plane is illuminated, because of path length differences of the traversing nuclei. It can be recovered by tracking the position of each event on the scintillator from the position and angle information provided by the [[Detectors#Cathode Readout Drift Chambers (CRDC)|CRDC]] detectors. The plastic scintillators can withstand maximum rates up to 1 x 10<sup>6</sup> particles per second. |
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| Each detector consists of two windows mounted on frames, two printed circuit boards (PCB) and an anode frame. Each PCB is made of un-masked G-10, and includes a field shaping foil to ensure a uniform field in the active region of the detector. Two G-10 spacers are laminated to the board on each side. The shaping foils are made of 1.9-mm pitch evaporated aluminum strips perpendicularly oriented to the electric field. The anode frame includes a glued cathode grounding plane, an anode wire running across the field, and a Frisch grid. Cathode pads are located in front of and behind the anode wire. The pads have a pitch of 2.54 mm. The anode frame is sandwiched between the two printed circuit boards with two spacers in between, as shown in the figure below. | Each detector consists of two windows mounted on frames, two printed circuit boards (PCB) and an anode frame. Each PCB is made of un-masked G-10, and includes a field shaping foil to ensure a uniform field in the active region of the detector. Two G-10 spacers are laminated to the board on each side. The shaping foils are made of 1.9-mm pitch evaporated aluminum strips perpendicularly oriented to the electric field. The anode frame includes a glued cathode grounding plane, an anode wire running across the field, and a Frisch grid. Cathode pads are located in front of and behind the anode wire. The pads have a pitch of 2.54 mm. The anode frame is sandwiched between the two printed circuit boards with two spacers in between, as shown in the figure below. |
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| {{:wiki:crdc-section.jpg?600 |Cross section of a CRDCs.}} | {{:wiki:crdc-section.jpg?600|Cross section of a CRDCs.}} |
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