Testing of C-layer bottom hole counters

A.Ito, J.Negret, B.Satyanarayana

June 30, 2003 D0 Muon Meeting 2

Introduction

Wide

• 92.270” X 33.282”

• 18 deep grooves

• 6 fibers per groove

Narrow

• 92” X 15.75”

• 49 flat grooves

• 4 fibers per groove

• Total 8 counters; 4 wide and 4 narrow type

• BC404 0.594” thick scintillator and BCF-92 WLS fibers

• Readout by twin Meltz PMTs

June 30, 2003 D0 Muon Meeting 3

Tests• Radioactive source

– Mapping the counter with source

– Comparison of counter responses to the source

– Detailed scans of the counters

• Cosmic tests– Counter efficiencies for cosmic muons

– Time delay measurements

• Response to LED pulser input

All tests done with the same set of PMTs

June 30, 2003 D0 Muon Meeting 4

LED pulser tests

• Using two fibers from LMB driven by SLP simulator

• LED drive amplitude (DC+AC) 12.7V

• Average pulse height = mV

June 30, 2003 D0 Muon Meeting 5

Cosmic tests

• Efficiencies for cosmic muons: > 99%

• Time difference in response between the centre and the edge of the counter: ~5.5nSec

• Problem with cosmic showers

• Trigger modified to include a veto

June 30, 2003 D0 Muon Meeting 6

Summary

• No problems noticed with counters

• Marked PMTs installed on the counters

• PMT voltages set to produce minimum of 100 mV signal anywhere on the counter

• LED pulser tests are also repeated

• Counters should be ready to go in a day or two