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detectors [2015/04/21 17:40]
pereira [Plastic scintillators] |
detectors [2015/04/21 17:43]
pereira [Tracking Parallel Plate Avalanche Counters (TPPAC)] |
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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_station|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_station|object station]] (S800_OBJ) and at the [[Stations#focal_plane_station|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 __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 connected to photomultipliers [[EMI 98807B]] in both ends (up and down). The time signal from the E1 scintillator is calculated as the average time signal from each photomultipliers. | [[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 connected to photomultipliers [[EMI 98807B]] in both ends (up and down). The time signal from the E1 scintillator is calculated as the average time signal from each photomultipliers. |
| 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. | 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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| ===== Tracking Parallel Plate Avalanche Counters (TPPAC) ===== | ===== Tracking Parallel Plate Avalanche Counters (TPPAC) ===== |
| Some experiments are particularly sensitive to the incoming positions and angles of the nuclei impinging on the target. Two tracking parallel plate avalanche counters (TPPAC) are installed in the [[Stations#Intermediate Plane Station|intermediate plane station]] of the [[Introduction#Analysis Line|analysis line]]. The position and angles measured with both TPPACs are transformed into the corresponding coordinates in front of the target, using the transfer matrix of the second half of the analysis line. The analysis line [[Magnets#Spectrograph Dipole|dipole magnets]] downstream of the intermediate image plane filter the particles produced in the tracking detectors, which would otherwise contaminate the data. | Some experiments are particularly sensitive to the incoming positions and angles of the nuclei impinging on the target. Two tracking parallel plate avalanche counters (TPPAC) are installed in the [[Stations#Intermediate Plane Stations#Intermediate Plane Station|intermediate plane station]] of the [[Introduction#Analysis Line|analysis line]]. The position and angles measured with both TPPACs are transformed into the corresponding coordinates in front of the target, using the transfer matrix of the second half of the analysis line. The analysis line [[Magnets#Spectrograph Dipole|dipole magnets]] downstream of the intermediate image plane filter the particles produced in the tracking detectors, which would otherwise contaminate the data. |
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| Each TPPAC has an active area of 10 cm x 10 cm and is filled with isobutane at a typical __pressure of 5 torr__. The detector consists of a cathode foil with a series of aluminum strips oriented in the non-dispersive direction, followed by an anode plate and a second cathode foil with the strips oriented in the dispersive direction. A total of 128 pads are connected to the strips of each cathode foil. The x and y positions are determined from the charge distribution on the pads. The position calibration was done using the pad pitch of 1.27 mm. | Each TPPAC has an active area of 10 cm x 10 cm and is filled with isobutane at a typical __pressure of 5 torr__. The detector consists of a cathode foil with a series of aluminum strips oriented in the non-dispersive direction, followed by an anode plate and a second cathode foil with the strips oriented in the dispersive direction. A total of 128 pads are connected to the strips of each cathode foil. The x and y positions are determined from the charge distribution on the pads. The position calibration was done using the pad pitch of 1.27 mm. |
