The Detectors

1. Scintillator
Bicron 408 (diamond mill finish)
decay time 2.1 ns
light output 64%
atten. length 380 cm
cost $85/liter

2. Light Pipe
UVT acrylic lucite
polished/machined in a single piece

3. Amperex XP2262 Phototube
4.4 cm
2.0 ns

4. Cern Model 4244 Tube Base

(0.10m x 0.1m x 1.6m)

total length 2.4 m

* 79 bars
* 37 paddles (same as above except ~1 cm thick)

Anode Current Measurements

For the values shown on the figure above, the following conditions apply: Click on the front face of an individual detector element to see a graph of its Count Rate vs. Threshold. Currently, graphs are available only for Layer 4 (the middle layer). For the graphs, the following conditions apply:
  • All currents are measured in microamps
  • Beam Energy=0.7 GeV
  • Detector Angle=60o
  • Distance from target center to surface of front wall=6m
  • Minimum ionizing particle signal was adjusted to 20mV amplitude of 10-11C charge
  • Target 3He length 40 cm
  • All currents are measured in 10 microamps
  • Beam Energy=2.3 GeV
  • Detector Angle=63o
  • Distance from target center to surface of front wall=6m
  • Target 3He length 40 cm

To Third Arm Working Group Home Page
Send comments to: Richard Lindgren , ral5q@virginia.edu
2/26/99 / Hall A Detector / Last Updated 4/22/99