October 22, 2008

Unpolarized Measurents:

A 2x4x8" aluminum brick was placed at the HRRL export in order to destroy the photon polarization. Rate measurements were made with the descriminator and HV settings used the past week. Then the constant fraction descriminator was replaced with a threshold descriminator on two detectors but not the reference detector.

ADC =0 => Reference Detector D

ADC = 1 => NaI

ADC=2 => Detector C

ADC = 3 => Detector A

channel # * 0.1675 ns/chan => ns

Matched HV and Threshold Descriminator

2 Runs were taken with the following settings

100 ms Threshold descrimnaotr

[math]HV_{Det A}[/math] =

[math]HV_{Det_C}[/math] =

Run 229

NaI spectrum monitoring the photon flux during run 229

The root commands

root [24] TH1F *RefDetRun229=new TH1F("RefDetRun229","RefDetRun229",800,0,800);
root [25] PhotoFis->Draw("evt.ADCval*0.1675 >> RefDetRun229","evt.ADCnum==0 && evt.LastADCval>0");

Will create histogram with 800 channels and 800 bins so we have 1 bin per channel (ns).

To normalize the data you need to integrate the NaI histogram. To do this a skeleton program is creates using ROOT which will loop through the ROOT ntuple using the command

PhotoFis->MackClass();

You will see a file called PhotoFis.C after you execute the above command within the ROOT interpreter window.

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Run 234

NaI spectrum monitoring the photon flux during run 234

If I normalize using the Reference detector I see

If I normalize using the NaI detector I see:

The Difference and Asymmetry measurements.

The above is just an example of how to analyze the data. Students should take my bad example and improve upon it.

The program I used to generate the above pictures from a ROOT file is given below.

I used the "MakeClass()" command within root to generate the skeleton program which has 2 files called Media:PhotoFis.h.txt and Media:PhotoFis.C.txt.

You define your histogram variables and the file you are opening to analyze in the file PhotoFis.h.

You create your histograms, loop over the ntuple entries , and perform histogram operations in the file PhotoFis.C

Asym

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