# Physics307L F07:People/Mondragon/Notebook/071024

note: power for LED is from - to +, not gnd to +

Verified the LED works power supply is Harrison Labroratories ewruhdkjdf GSA prop. 00029

PMT Voltage at -1900 V

We set the voltage to the pulser so we get 10.03+/- 0.02 khz

THE tAC SEEMS TO WORK, ADDING A DELAY TO THE SIGNAL SEEMS TO MAKE THE TAC OUTPUT A BIGGER SIGNAL the delay that the delay box puts into the signals is unnoticable on anb o-scope

### 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")

TimeCentoidFWHM
4ns24.13312.161
8ns67.7914.938
12ns108.213.329
16ns153.714.874
20ns192.614.841
24ns236.417.610
28ns276.515.903
32ns323.023.378
36ns360.318.118
40ns40421.038
44ns444.419.412
48ns490.525.0955
52ns530.121.614
56ns573.325.081

The curves we were seeing from the MCA looked Poissonish.

## Calculations

important!!! FWHM is not the error . It is related, however,

$\mathrm{FWHM} = 2 \sqrt{2 \ln (2) } \; \sigma \approx 2.355 \; \sigma.$

TimeCentoidFWHMCentroid error
4ns24.13312.16128.637
8ns67.7914.93835.18
12ns108.213.32931.4
16ns153.714.87435.0
20ns192.614.84134.9
24ns236.417.61041.5
28ns276.515.90337.4
32ns323.023.37855.0
36ns360.318.11842.7
40ns40421.03849.5
44ns444.419.41245.7
48ns490.525.09559.1
52ns530.121.61450.9
56ns573.325.08159.1

## Linefit/ Channel number to time conversion

$channel\,number=(10.53 \pm 0.69 \tfrac{channels}{s})(time\,delay) -(17.29 \pm 19.54)channels$ $time \, delay=(0.09495 \pm 0.00626 \tfrac{s}{channel})(channel\,number) -(1.641 \pm 1.861)s$