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Data acquisition techniques and development of testing equipment for the JLab Hall C 12 GeV kaon aerogel detector. Nathaniel Hlavin, Mike Metz. VSL Presentation. 19 August 2011. Outline. Brief Physics Motivation Data AcQuisition (DAQ) System Key component used for all tests Aerogel testing

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Nathaniel hlavin mike metz

Data acquisition techniques and development of testing equipment for the JLab Hall C 12 GeV kaon aerogel detector

Nathaniel Hlavin, Mike Metz

VSL Presentation

19 August 2011



Brief Physics Motivation

Data AcQuisition (DAQ) System

Key component used for all tests

Aerogel testing

Large diameter photomultiplier tube (PMT) uniformity tests

PMT gain tests

Physical motivation proton substructure

Physical Motivation: Proton Substructure

To understand further what makes up a proton, we use Generalized Parton Distributions (GPD).

They combine the spatial and momentum distribution of the quarks into one concise chart. Below are some examples based on models. We seek experimental confirmation. “x” is the fraction of the momentum of the quark over the momentum of the proton

Meson electroproduction

Meson Electroproduction

K+ or

Above dotted Line: Hard Scattering Process (QCD)

We can calculate this.

Below Dotted Line: GPD. This is what we want.

A high-energy electron beam releases a photon of a very high frequency. The high-frequency allows us to observe objects with greater detail.

The interaction of the photon and proton (pictured “GPD” here) results in a neutron (pictured here with momentum p’) and a meson (for example a pion or a kaon). For our proposed experiment, the meson would be a kaon.

We are able to detect/calculate the portions of the diagram above to dotted line, and from them we can contsruct the GPD. However, the meson released must conform with the Quantum Chromo Dynamic (QCD) theory of quarks.

Problematic pions

Problematic Pions

T. Horn et al., Phys. Rev. Lett. 97 (2006) 192001.

T. Horn et al., arXiv:0707.1794 (2007).

We know how to calculate the hard or perturbative QCD model, but our data for the pion spatial quark distribution does not match the QCD prediction.

Further experimentation with the kaon could provide data that matches the QCD prediction. The dotted prediction seems to doubt it.

Matching data would enable GPD construction to reveal the proton substructure.

The 12 GeV upgrade allows for kaon production above a Q2 value of 1, and even higher into the hard QCD range.

A.P. Bakulev et al, Phys. Rev. D70 (2004)]

Kaon aerogel detector

Kaon Aerogel Detector

Side View

Front View

Aerogel Panels

  • As a charged particle (kaon) passes through a substance (aerogel) faster than light passes through that substance, light is emitted.

  • This light is called Cherenkov light and can be thought of as a shock wave in the electromagnetic field. It is analogous to a sonic boom.

  • The light is collected by Photomultiplier Tubes (PMT) and converted into an electron signal by the photoelectric effect.

  • This signal is then amplified into a signal that can be analyzed.

  • An example image of a detector is pictured at right.



Cherenkov Light

Aerogel tests

Aerogel Tests

  • Several Properties need to be looked at

  • Measurements to verify Index of Refraction

  • Experiments to test light output, signal strength, etc.

Aerogel tests cont

Aerogel Tests (cont.)

  • Aerogel Properties Tested using cosmic muons.

  • Test setup must be light-tight.

  • Setup Constructed Here at CUA

Setup diagram

Light box

Electronics diagram aerogel testing

Electronics Diagram(Aerogel Testing)

Aerogel tests cont1

Aerogel Tests (cont.)

Data acquisition

Data Acquisition

  • Uses CODA 2.6.1 Software.

  • Runs on Scientific Linux CentOS 5.5

  • Interfaces with VME crate that boots from computer with Power PC VxWorks OS.

  • Connected to equipment/modules in CAMAC crate

  • Data analyzed by ROOT programs.

  • Software and some hardware acquired from JLab

Nathaniel hlavin mike metz

CODA 2.6

DAQ Setup

User == DAQ







Crate Controller

[various modules, etc.]




CAMAC Interface

Data acquisition1

Data Acquisition

Pmt uniformity tests

PMT Uniformity Tests

Large Diameter PMTs may perhaps output varying signals dependnig on area of photocathode struck with light.

Necessary to investigate Uniformity

LED attached to a two-axis stepper motor setup

Scans 10x10 grid and measures gain at each point

Thanks to Jack Segal at JLab for technical support

Uniformity test setup

Pmt uniformity tests cont

PMT Uniformity Tests (cont.)

Data analysis application

Pmt gain testing

PMT Gain Testing

  • Pulsing LED Used to test PMT Gain

  • Gain: Amount of electrons output by PMT when single electron is emitted from photocathode window.

  • The “multiplier” in photomultiplier tube.

Pmt gain tests

PMT Gain tests

Data analysis software ROOT used to fit curves to the data

Pedestal: trigger signals without PMT signal

Single-electron peak: charge output by the PMT when a single photoelectron is released

Gain vs hv

Gain vs. HV



  • PMT and Aerogel Characterization to continue

  • ~70 PMTs to test and ~200 L Aerogel

  • Detector Construction to begin at CUA

  • Upcoming Use in approved JLab experiment E12-09-011



  • Thanks to Dr. Horn for her tireless support and mentorship

  • JLab staff: Dr. Hamlet Mkrtchyan, Dr. Vardan Tadevosyan, Dr. David Abbott, Dr. Jack Segal, Dr Ibrahim Albayrak

  • VSL for technical support and hardware.

  • CUA for the opportunity to conduct research.

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