LW Detector
General Specs
Thin lead sheet converts gamma rays to e plus / e minus pairs which create cherenkov radiation in the areogel in the head of the detector. A light tight 10 x 10 cm pipe lined with aluminium coated mylar guides the cherenkov radiation to a PMT at floor level (far from the beam level). The PMT is also shielded for additional protection. The detector is operated at 1250V and a 30 m heliax cable is used to relay the signal to the LW Hut where the signal is first attenuated and then digitised by a gated 14 bit ADC.
- 7.3 mm lead (optimal thickness) - see LD's thesis
- 4 x layers of 5 x 5 x 1 cm Aerogel - unknown whether single layer best
- Hamamatsu R887
- Typical attenuation 8 - 16 dB
Diagrams
History
Date |
Action |
March 2012 |
Post earthquake check |
Head rebuilt |
Aerogel Holder rebuilt |
Two photodiodes installed in head |
September 2010 |
Rebuilt / Relocated |
Relocated detector to immediately after B5FF |
Rebuilt detector with additional horizontal arm at top |
Reduced areogel area to 5 x 5 cm |
Areogel original was 10 x 10cm - quartered and stacked this |
Removed supporting base structure |
June 2010 |
Head modification |
Reduced lead area to 4 x 4 cm from 10 x 10 cm |