Difference between revisions of "Sampling Calorimeter"

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(HV control)
(HV control)
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Revision as of 10:54, 7 February 2013


Test setup

Nomenclature of the modules (could be changed)

In order to identify the different modules, the following structure is used:



  • X = O (outer) or M (middle)
  • YY= 01, 02, 03, 04 ...
  • Z (only Middle modules) = A, B, C, D

HV control

HV modules were tested by running -2000V across a 5 Megaohm resistor. we measured the voltage out and current out. The histogram below is the percent error in expected current values. The PDF is the charts holding the data taken during the test. Once the HV mosules are back in the TEDF another (more accurate) test may or may not be performed.

File:HV TEST2.pdf


Light Leaks sealing

The modules were sealed from light leaks with the use of black tape. To check the sealing, the output of the PMT was measured with an micro-amperimeter, before and after the cover with tape. In top of the pipe, where the PMT is allocated, a gum stopper with slits for the cables, are placed. After many checks it was found that:

  • the main light leak come for the joint of the module with the PMT allocation pipe. (Covering it, reduce the current drain from PMT aproximatly in 1-2 orders of magnitude)
  • covering the cap of the pipe, doesn't show significant improve.
  • covering with tape the side corners of the module, the joint of the top and bottom plastic caps and the union of the pipe with the module reduce the current drain from PMT in 4-5 orders of magnitude.

Outer Modules

For the outer modules, the same PMT was used, with a voltage of 1000 V (max 1900 V) to avoid damage to the PMT.

Module Current before Current after
O-01 15.2 μA 0.3-0.2 nA
O-02 10.9 μA 0.3-0.1 nA
O-03 48.5 μA 0.7-0.5 nA
O-04 N/A 2-1.7 nA
O-05 34.4 μA 2-1.4 nA

Middle Modules

For the middle modules, the same PMT was used, with a voltage of 1000 V (max 1900 V) to avoid damage to the PMT.

Module Current before Current after
M-01-A 10.9 μA ~0.5 nA
M-01-B 24.2 μA ~0.2 nA
M-01-C 20.9 μA ~0.2 nA
M-01-D 7.5 μA ~0.2 nA
M-02-A 38.5 μA ~0.7 nA
M-02-B 13.1 μA ~0.4 nA
M-02-C 30.5 μA ~0.3 nA
M-02-D 10.7 μA ~0.2 nA
M-03-A 23.9 μA ~0.7 nA
M-03-B 6.45 μA ~0.6 nA
M-03-C 3.8 μA ~0.3 nA
M-03-D 19.2 μA ~0.3 nA
M-04-A 13.2 μA ~0.7 nA
M-04-B 6.69 μA ~0.5 nA
M-04-C 5.3 μA ~0.5 nA
M-03-D 7.8 μA ~0.45 nA


This is the flow chart for the current trigger logic. We are using 3 scintillators; 1 double sided (2PMTs) on top, and 2 separate scintillators on bottom. The difference between threshold voltages is to match gains, this was not done by adjusting HV since presently using HV units with dual outputs for one HV setting.

Trigger Logic Chart

Scheme of cables

Scheme of the HERA-B modules. The orientation is as follows: top view with the rack modules at its left. Each module is indicated by its nomenclature (explained above), the DAQ and HV cable number (in red) and the signal cable (sgn).

Red: the number of the channel (for DAQ and HV label). Sgn: cable signal label.