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hv_bias [2014/11/19 11:32]
pereira [General Information]
hv_bias [2019/01/23 13:44] (current)
pereira
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-===== General Information ​===== +===== HV Remote control ​===== 
-The [[Detectors#​Tracking Parallel Plate Avalanche Counters (TPPAC)|TPPACs]], ​the [[Detectors#​Ionization Chamber|Ion Chamber]], ​and the [[Detectors#​Cathode Readout Drift Chambers (CRDC)|CRDCs]] ​have ISEG power supplies run through a single VME-based bias control. The computer interface for this bias control -- the S800 Detector HV Control -- is typically run on the **devop1** computer ​in data-U6 and is started ​by clicking on **S800 HV** under the Operations option ​on the taskbar. The [[Detectors#​Plastic scintillators|Object scintillator]] and the [[Detectors#​Plastic scintillators|FP Scintillator]] are each controlled separately ​as described below under the sections for each detector.+The high-voltage of the [[Detectors#​Tracking Parallel Plate Avalanche Counters (TPPAC)|TPPACs]],​ [[Detectors#​Ionization Chamber|Ion Chamber]], the [[Detectors#​Cathode Readout Drift Chambers (CRDC)|CRDCs]], [[Detectors#​Plastic scintillators|FP Scintillator]],​ and [[Detectors#​Hodoscope|Hodoscope]] are remotely controlled via GUI control ​panel (see figure below). The GUI can be opened from the desktop of the [[Software#​u6pc5 (data U6)|u6pc5]] control computer by log in as s800 user and clicking in the icon **High Voltage**, or from a Linux terminal (again, log in as s800 user) by typing ''/​usr/​bin/​wish mpod.tcl''​ from directory ​**/​user/​s800/​Documents/​Run/​s800mpod**. This application allows also to set a maximum limit in the detector current. The voltages of these detectors depend ​on the Z of the fragments to be measured and their energy. The figure below shows the HV GUI during experiment e10002, which used Si-26 and Al-25 fragments at around 115 MeV/u. These voltages can be used as a reference before starting an experiment. However, ​the final values will have to be modified during the beam tuning in order to optimize the performance of the detectors
  
 +{{:​wiki:​hv-gui.png?​700|GUI control panel of the S800 detectors HV}}
  
-{{:​wiki:​hv-gui.png?​800|GUI control panel of the S800 detectors HV}} 
-===== Object Scintillator ===== 
-The bias for the object scintillator is controlled via the H.V. power supply {{:​wiki:​Manual_Canberra_HV_3002D.pdf|Canberra model 3002 D}} located in the crate to the right of the data-U6. The voltage will be adjusted at the beginning of the experiment. This scintillator has to be turned off or put on "​standby"​ when entering the vault due to its sensitivity to light. 
  
-===== FP Scintillators ===== +Other examples of HV values ​used with different fragment beams are:
-Only the fist two scintillators are typically ​used since in most cases particles do not reach beyond the second detector. The biases for the anode and the drift electrode ​are each controlled separately via the S800 Detector HV Control. To protect the scintillator PMT bases from damage from discharge under poor vacuum conditions (for example, during a window break on one of the nearby gas detectors), the 12-Volt supply for the PMT bases is interlocked to switch off if the pressure in the focal plane box rises above some minimum value as read by an ion gauge. The ion gauge controller (a black box with an LED digital display) is mounted on the south support structure for the focal plane chamber. ​ The interlock condition is communicated to the PMT bias supply via a multi-pin “D” connector on the back of the controller. If the ion gauge is off, the interlock condition prevents biasing of the scintillator. It is possible to manually override the interlock condition for testing by connecting a “cheater” connector in place of the ion gauge controller to the cable for the interlock.+
  
-===== Ion Chamber ​===== +* **CRDC1 and CRDC2**:  
-The biases for the anode and the drift electrode are each controlled separately via the S800 Detector HV Control. Parts of this detector rely on the same 12-Volt power supply used to power the bases of the FP Scintillator PMTs. If the vacuum-based interlock condition for protecting the FP Scintillator PMTs is triggeredthe 12-Volt power supply will not be available for the Ion Chamber.+   * For He-3 @ ~130 MeV/u: CRDC1 (Anode=1120 V, Drift=1000 V); CRDC2 (Anode=1120 V; Drift=1000 V) 
 +   * For Be-12 @ ~30 MeV/u: CRDC1 (Anode=970 V, Drift=1000 V); CRDC2 (Anode=970 V; Drift=1000 V) 
 +   * For Ar-34 @ ~80 MeV/u: CRDC1 (Anode=860 V, Drift=1000 V); CRDC2 (Anode=840 V; Drift=1000 V) 
 +   * For Zn-58 @ ~44 MeV/u: CRDC1 (Anode=740 V, Drift=1000 V); CRDC2 (Anode=740 V; Drift=1000 V) 
 +   * For Rb-74 @ ~40 MeV/u: CRDC1 (Anode=650 VDrift=1000 V); CRDC2 (Anode=650 V; Drift=1000 V) 
 +   * For U-238 (88+) @ ~70 MeV/u: CRDC1 (Anode=570 V, Drift=1000 V); CRDC2 (Anode=570 V; Drift=1000 V)  
 +     
 +* **FP scintillator (E1 up and E1 down)**:  
 +   * For He-3 @ ~130 MeV/u: UP (1790 V); DOWN (1760 V) 
 +   * For Be-12 @ ~30 MeV/u: UP (1770 V); DOWN (1700 V) 
 +   * For Ar-34 @ ~80 MeV/u: UP (1580 V); DOWN (1510 V) 
 +   * For Zn-58 @ ~44 MeV/u: UP (1400 V); DOWN (1340 V)  
 +   * For U-238 (88+) @ ~70 MeV/u: UP (1180 V); DOWN (1280 V)
  
-===== CRDCs ===== +* **IC**: ​ 
-Each of the two detectors, CRDC1 and CRDC2, has a separate bias control for the anode and the drift electrode via the S800 Detector HV Control. Please keep in mind that a change in the drift voltage of the CRDCs strongly affects the drift velocity of the electrons and a new mask calibration has to be done to be able to determine the y position of particles. Apart from the CRDCs, it is important to bias the electrostatic gate (see section [[Detectors#​Cathode Readout Drift Chambers (CRDC)|CRDC]]). The power supply is located in the crate to the right of the data-U6; the typical voltage is 26 V+   * Typically 200 V
-===== TPPACs ===== +
-The bias of each of the two detectors, PPAC1 and PPAC2 is controlled individually via the S800 Detector HV Control. There are two types of detectors used for the TPPACs: either the “classic” PPACs or [[Detectors#​Tracking Parallel Plate Avalanche Counters (TPPAC)|multi-strip PPACs]] with individual strip readouts for handling higher rates. There is not a difference between the two detector types in terms of how the data is used.  They do differ in terms of electronics and acquisition.+
  
 +===== HV Manual control ====
 +Apart from the detectors listed above, the voltages of the [[Detectors#​Plastic Scintillators|object scintillator]] ​
 + and the electrostatic gate of the [[Detectors#​Cathode Readout Drift Chambers (CRDC)|CRDCs]] are adjusted manually. ​
  
 +The bias for the object scintillator is controlled via the H.V. power supply {{:​wiki:​Manual_Canberra_HV_3002D.pdf|Canberra model 3002 D}} located in the crate to the right of the data-U6 (see figure below). The voltage will be adjusted at the beginning of the experiment. This scintillator has to be turned off or put on "​standby"​ when entering the vault due to its sensitivity to light. The voltage used for this detector depends on the fragment nuclei that will be measured. Check with **Daniel Bazin** for a reference value.
 +
 +In order for the [[Detectors#​Cathode Readout Drift Chambers (CRDC)|CRDCs]] to work, it is necessary to bias their electrostatic gate. This is done via the H.V. Tennelec power supply located on the left side of the object-scintillator Canberra power supply (see figure below). The typical value is 20 V.
 + 
 +
 +{{:​wiki:​nim-crate2-du6.jpg?​400|NIM crate 2 in data-U6}}
  
hv_bias.1416414763.txt.gz · Last modified: 2014/11/19 11:32 by pereira