Physics307L:People/Trujillo/LAB NOTEBOOK/071024

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Speed Of Light

(week 1)

NOTES:

Set up as described in the lab procedure. Tomas and I verified that the PMT was operating (green light seen).

Set Up

LED pulser voltage: 153.9

With the O Scope, we verified the start and stop TAC signals. We also measured a pulse frequency of 8.4kHHz. We adjusted the PMT voltage to get the pulse frequency of exactly 10.01kHz (+/- .02kHz)

System Calibration: We will use the delay box got measure the insertion loss. The TAC seems to be working and we confirmed the delay box works by using the MCA. The histogram shifts when a delay switch is turned (YES!). After configuring the MCA we started taking cal data

TAC Settings/High Voltage for PMT

Range = 100

Multiplier = 1

SCA Window = 811

SCA Lower Level = 48

Start and Stop = Anti

Output = Out

Voltage = 1500 + 497.1

Calibration Data (needed or "Time Walk")

Time Centoid FWHM
4ns 24.133 12.161
8ns 67.79 14.938
12ns 108.2 13.329
16ns 153.7 14.874
20ns 192.6 14.841
24ns 236.4 17.610
28ns 276.5 15.903
32ns 323.0 23.378
36ns 360.3 18.118
40ns 404 21.038
44ns 444.4 19.412
48ns 490.5 25.0955
52ns 530.1 21.614
56ns 573.3 25.081

The curves we were seeing from the MCA looked Poissonish.

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