Specs, Types, and Locations of Small PMTs¶
The MRD, fully instrumented, uses 362 PMTs (182 PMTs in 7 horizontal planes and 180 in 6 vertical planes).
Break down of what is left of the MRD hardware (something to think ahead about for RunII)
Even layers (z = 2, 4, 6, 8, 10, 12) --> all PMTs&paddles remain (for both x = 0,1)
Odd layers (z = 3, 5, 7, 9, 11)
Layer z = 3 --> missing PMT&paddle at (x = 14, y = 0) --> known
Layer z = 5 --> NO PMTs&paddles remain (all are missing) (for both y = 0,1)
Layer z = 7 --> missing PMTs&paddles for x = 5, 6, 7, 8, 9 (for both y = 0,1)
Layer z = 9 --> all PMTs&paddles remain (for both y = 0,1)
Layer z = 11 --> NO PMTs&paddles remain (all are missing) (for both y = 0,1)
- EMI 9954KB (from KTeV): ~135 channels
- EMI 9939B (Positive HV): 26 channels
- EMI 9839B: ~20 channels
- RCA 6342A: ~80 channels
The missing 100 were returned to Rochester. We will track down replacement tubes at FNAL.
We have inspected the SciBooNE Hall. We were able to easily identify the positive HV tubes (EMI 9939B), as they were labeled and denoted with yellow electrical tape around the boarder. There was exactly on horizontal layer (both sides) instrumented with the 26 9939B's.
There was also a layer with 26 PMTs that had a "dimpled" metal sheath, and we counted 104 of some standard looking base. This does not map perfectly to the numbers above.
PMTs (and cables) are labeled by location:
where xx labels which of the 4 sides of the square perimeter of the detector, yy is the height, and zz is the number of layers in.
even z are horizontal
We were able to find the cable for MRD channel 034 and measured the base resistance to be 3.17 Mohm.
At 1400 V MRD channel 022 (also 3.1 Mohm) drew 0.71 mA current
At 700 V " " " 0.354 mA
consistent with an operational R of 1.97 Mohm
At 1400 V MRD channel 002 drew 0.70 mA current
At 700 V " " " 0.350 mA
consistent with an operational R of 2.0 Mohm
We believe that these are of the 9954KB vintage
Regarding cabling we found that two different shades of green corresponded to the horizontal and vertical planes:
Dark green corresponded to the vertical planes and light green to the horizontal.
There is a collection of splitter panels that go from BNC-in to BNC-out + LEMO-out. The LEMO connectors would then continue to the TDC electronics, while the BNC connector on the back would continue to the delay and then to patch-panels on the bottoms of the racks where ribbon cables would lead to the ADC electronics.
The splitter panels are missing one row.
There is an additional patch panel that goes directly from BNC-in to LEMO-out. This patch panel (on the rack furthest to the right) provided LEMO cables to feed into an amplifying splitter, where half the signal goes to the TDC and the other half goes to a LEMO-to-BNC patch panel into the delay cables and around to the ADC. This second path is for the dark-green vertical PMTs which are low gain and need amplification. The light green horizontal cables need only a passive splitter and no amplification. The second LEMO-to-BNC patch panel is missing, as are the amplifiers.
For the low gain PMTs - they used 10 channel NIM amplifying splitter