pmt testing at jmu - automation and afterpulsing · pmt testing at jmu - automation and...
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PMT Testing at JMU -Automation and Afterpulsing
Tara JobinWilliam KemmererEric MoellerWilliam Shaver
11/11/2016
Dr. Ioana NiculescuDr. 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
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