Mip analysis for the 2007 AuAu Preshower data


This is an analysis of the ADC spectra for the BPRS, it has three parts

1: Analysis of the ADC -Pedestal*rms*3.5 spectra over PMT crates

2: Analysis of the Spectra soft ID by soft ID

3: A basic slope analysis of the data

Data sample:

The sample contains data with the swaps from 2006 and without swaps

The data has the trigger ID range from 200000-200013

Tower adc must be greater than 2.5 pedestal

Runs less than 8088012 were dropped

About 2500 files have been analised from the HPSS

PMT ADC spectra with pedestal subtracted

The pedestals were subtracted and each PMT crate was plotted. The idea would be that on a colour 2D histogram that mip peaks would be easy to see as "red" areas close to the ADC=0 axis

The MIP peaks in the ADC spectra seem to show up as positive slopes (red zones) in bands of 20 channels on the background. Going through the plots one by one, hot and dead channels cut into this pattern and can be used to estimate the amount of the preshower that will be lost in the final analysis. Also, with some hot PMT boxes, the pattern can be seen in the background and could be used to salvage data in zones of bad channels.

I noticed that there were gaps at the "wrap" of the BPRS round the barrel (see PMT 30 for example), any gaps here are likley a bug, not dead channels.

ADC, pedestal subtracted for PMT crate 9

Plots for the preshower NO SWAPS

Plots for the preshower WITH SWAPS from 2006

Plots for the tower

All plots in tar.gz file

Soft Id preshower adc values

The adc, pedestal subtracted was first plotted vs. the momentum reconstructed from the tpc. This did not show any clear signs of seperating the tail from the possible mip peak so was dropped in further analysis

Note: the large peak is not the pedestal when compared to the data base.

The following plots are produced for each soft Id over the whole bulk of the data.

The fits are made to give an idea of gain adjustments needed for the PMT boxes.

The function is [0]*exp(-0.5*((x-[1])/[2])**2)+[3]*exp(-[4]*x)

Top left ADC raw no swap

Top right ADC raw with 2006 swap

Mid left ADC, pedestal subtracted, no 2006 swap, basic fit

Mid right ADC, pedestal subtracted, with 2006 swap, basic fit

Bottom left ADC, pedestal subtracted, of the tower


All plots in tar.gz file


The fits from the function seem to work most of the time but will probably need to be tuned

Here is an example of a first fit

Par 1 swap Mip peak

Par 4 swap Exponential slope

Par 1 no swap Mip peak

Par 4 no swap Exponential slope

I will add magnified versions of this on PMT boxes, for the moment, if you want to look, here is a link to the fits in a root file:

Root file for slopes (right click and Save As)