Noise Scan Test & Flexible Web Testof STRAW Tracker

Thomas Pak26-03-2012

CERN / NA62(George Mason University)

Content1. Front-End Electronics Noise Characteristics2. The noise_scan_tp Script3. Flexible Web Testing Method4. Near-Future Perspectives & Anticipations

1. Front-End Electronics Noise Characteristics

• Thermal noise of the straws

• Shot Noise of the straws

• It seems the above 2 will be taken care of by the CARIOCA shaper. (Yet to be tested and investigated?)

• High Voltage Input Capacitor Noise

• CARIOCA’s internal white-noise

2. noise_scan_tp Script• Originally written by Peter Lichard• Assumes Gaussian white-noise of CARIOCA’s input channels• Sends given number of test triggers with given threshold

voltage to scans how many actually got registered at each channel.

• 2 scan modes– Mode 1: Sends triggers to all channels at the same time (short)– Mode 2: Send triggers to each channel individually (long)

• Outputs in …/noisescan_plots/ folder)– .txt file # of Pulses Registered in each channel & the white noise

characteristics (mu’s and sigma’s) fitted for the scan data for each channel

– .dat file to be used for gnuplot– .gp script file for doing gnuplot– Automatically plots white-gaussian noises for all channels

2. noise_scan_tp Script:Mathematical Background

• Number of pulses expected to be registered at a channel

• The script linearizes the above to find Vp and σ.

• So far, the result have been:– Vp : ~0.805V σ : ~0.014V

• But I expect this to somewhat larger, when flexible-webs and straws are attached. (Yet to be tested)

3. Flexible Web Test1. So far about 20 of them tested (About 20/week can be

done); Test-Method Documentation underway!2. The testing method is straightforward; put HV(2.2kV)

flexible-web, and scan (using tdc_scan script) if there’s any shot-noise(s) accidentally being registered.

3. The HV capacitor is extremely sensitiveneeding cleaning and extra-care in handling

4. Strange Bahaviors- Leaving the webs overnight seem to stabilize the HV capacitors- For some reason, increasing to a higher voltage (2.4V) for 10

minutes and bringing back down to 2.2kV would expedite the stablizing process. This method was used.

3. Flexible Web Test: Basic Procedure

– Clean the Frame

– Installing the webs with an insulator between cathodes and anodes

– Closing the Front-End cover

– Injecting CO2/Ar gas mixture

– Put 2.4kV on the web for 10 minutes

– Reduce HV to 2.2kV and do tdc_scan

4. Near-Future Perspectives and Anticipations

– Uniformity of each CARIOCA chip’s noise_scan performance seems called for.

– Noise_Scan would be needed when straws and webs are all connected together This will determine the confidence level of a pion track detection (Since the decay mode is rare (~10-9) to begin with.)

– Previous CARIOCA performance with a delta input (for muon tracks) had been conducted. (It assumes certain pulse characteristics.) If there’s a similar study done for STRAW tracker, it would be great to study the confidence level of this particular detector.

Acknowledgement

– Dr. Augusto Ceccucci– Hans Danielsson– Peter Lichard– Antonino Sergi– Georgios “the Master” Konstantinou– Johan Morant– All others Thank you, for the help and support to bring me up to speed

thus far!