PMT Testing at JMU - Automation and Afterpulsing PMT Testing at JMU - Automation and Afterpulsing Tara

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  • PMT Testing at JMU - Automation and Afterpulsing

    Tara Jobin William Kemmerer Eric Moeller William Shaver

    11/11/2016

    Dr. Ioana Niculescu Dr. Gabriel Niculescu

    James Madison University

    Eric Moeller, SESAPS 2016

    FU-84 PMTs

  • Outline

    11/09/2016 Eric Moeller, SESAPS 2016

    ● Motivation ● Our Setup ● Automation ● Progress ● Afterpulsing ● Future Plans

  • Motivation

    ● JLab Hall A ○ ECAL

    ● 8,000 PMTs to test

  • Our Setup

    ● Custom-built ● Light-Tight

  • Our Setup

    11/09/2016 Eric Moeller, SESAPS 2016

    Reflecting surface

    Light

    LED

    ● PMTs held vertically ● LED in the middle and

    spread by mirror ● Includes a 2-inch

    weakness PMT ● Takes up much less

    space

  • Our Setup

    11/09/2016 Eric Moeller, SESAPS 2016

    ● Slow to set up ● Many different

    computer commands

    ● Many chances to make mistakes

    ● Data analysis by hand

    ● Required excessive time and attention

    ● Time to automate!

    Screenshot of the desktop mess

  • Automation

    11/09/2016 Eric Moeller, SESAPS 2016

    ● Only ONE command! ● Combination of C and Python ● Opens three terminals

    ○ HV Controller (CAEN 5527) ○ Raspberry Pi ○ Data Acquisition (CODA)

  • Automation

    11/09/2016 Eric Moeller, SESAPS 2016

    ● Combination of ○ Shell scripts ○ Expect ○ C++

    ● Automatic pedestal runs ● Runs through multiple

    voltages ● Automatic ROOT analysis ● We use a VME-based DAQ ● Produces Summary Graphs

  • Automation

    11/09/2016

    ● More efficient ● More accurate ● More time for

    homework

  • Afterpulsing ● What is afterpulsing? ● Why is afterpulsing

    important?

    ● JLab signals at 5-10 kHz

    ● Occurs at the first dynode

    ● Ionizes gas within the tube

  • 11/09/2016

    Afterpulsing

    ● We shift the gate on our DAQ window ○ Quad gate

    ● Testing with blue LED ● No amplification ● PMT baking

    ○ No significant difference!

    ● Still test 1100V-1500V ● Yes, we even

    automated this!

  • Summary

    11/09/2016 Eric Moeller, SESAPS 2016

    Picture of PMT pallets

    Picture of aluminum setup

    ● Hall A ECAL ● Setup ● Automation ● Afterpulsing

  • Thank You!

    11/09/2016 Eric Moeller, SESAPS 2016

    ● JMU Physics and Astronomy Department

    ● NSF

  • 10/27/2016

    ECAL Specs • Function: Detect 4-5 GeV Electrons • Energy resolution: σ/E 10% or better for 3.5 GeV • Spatial resolution: 6-8 mm (2 mm if using

    upstream coord. Detector – GEMs) • Full Luminosity: 26-29 degrees, 8 x 1038 Hz/cm2

    • Trigger: Overlapping segments correlated w/ the proton. Trigger at threshold > 75% of elastic peak

    • 1500-2000+ Lead-glass blocks, readout by FEU84 photomultiplier tubes

    • Need to test (@JMU) : Gain vs HV, Relative Q.E., AfterPulsing, heat damage

  • Our Setup

    11/09/2016 Eric Moeller, SESAPS 2016

    • Wooden PMT holder. • Light source “far away”. • Use geometric optics to predict

    LL. • No +ve PMT placement. • Setup too long for our dark box.

    • Foam PMT holder. • Circular PMT placement. • Light source “farish away”. • Use geometric optics to predict LL. • Still no +ve PMT placement.

    • 3D printed PMT holder. • Circular PMT placement. • +ve PMT placement (stop) • PMTs sag if not supported at the back.

  • Template

    11/09/2016 Eric Moeller, SESAPS 2016