energy resolution of a parallel- plate-avalanche-chamber kausteya roy professors e. norbeck and y....
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Energy Resolution of a Parallel-Plate-Avalanche-Chamber
Kausteya Roy
Professors E. Norbeck and Y. Onel
Background: Overview of Particles
• Basic types: fermions and bosons• Fermions- particles of matter, half integral spins• Types of fermions
– Leptons, weakly interacting particles, ex: electron– Hadrons- made up of quarks, strongly interacting
particles, types such as baryons, mesons– Ex of baryons: protons, neutrons
• Bosons- particles of force, integral spins• Fit into the Standard Model theory
Background: Future of Particle Detection
• Standard Model accounts for three of the Four basic forces
• Electromagnetic- photon
• Weak Nuclear- W boson
• Strong Nuclear- gluon
• Gravitational force is unaccounted for
• Theorized-Higgs boson and Graviton
Background: General Principle of Electromagnetic particle detectors
• Incoming particle decays into charged leptons or baryons
• Detectable using magnetic fields F=qvB, where q= charge on particle
• Other types: decelerate through a Voltage, such that qV=(1/2)mv2, or for relativistic speeds qV=mc2γ
• PPAC is a type of proportional counter, which uses wires to conduct signals
Background: A Future Particle detector
• PPAC is a type of low pressure gas detector• Two parallel plates filled with low pressure gas and a relative
electric potential of 930 volts• Electrons enter chamber and generate shower of knocked off
electrons• Called electron “avalanche”• Since an individual electron has too small a charge to be measured,
an avalanche is required to measure charge• Avalanche moves in direction determined by Voltage, which
generates an electric field across plates
Background
Background: Electron Avalanche Formula
• General form of Townsend’s law
• N(α,x)= exp(α,kx) where a is the Townsend coefficient and x is the distance within the detector
• For electron diffusion within electric field
• W= (-4π/3)(e/mN)(E/P) S v^2/o(m)df dv/dv
Advantage of PPAC
• Resistant to Radiation
• Simple to use
• Signal termination expected to be quick
• Distinct pulses
• Easy to analyze electronically
• High GeV Detection
Purpose of Experiment
• Test for PPAC time resolution
• Time required for second PPAC to register signal-expected 50nsec
• Test for PPAC Energy Resolution
• Closeness of pulses in both PPACs
• Test of voltage gain-expected 30mV
Electronic Setup (Timing Resolution)
Discriminators Cable Delay TDC
Stop
Start
RadioactiveSource
PPAC Dual-Output Preamp
-750V
The Radioactive source emits Beta particles, which emulate a high energy hadron shower.
Electronic Setup (Energy Resolution)
RadioactiveSource
PPAC Dual-Output Preamp
ADC
ADC
SpectroscopyAmplifiers
-750V
Preliminary – Electronics Energy resolution
Data Collection: Useful Equations
• The equipment detects voltage, as well as time continuum for pulse
• Energy derivation
E= (1/R) t1St2 V(t) dt
R= Test Resistance, usually 50 ohms
Data: Timing Resolution
Avg Signal 15nsec
Data: Energy Resolution
Avg. Gain: 55mV
Data: Further Testing
• Testing at Fermi lab• 4 TeV proton beam• Further test-beams
with pions and mesons
• Pions- higher charge than electrons
• Mesons- quark, anti-quark pair
Conclusions
• Good Timing resolution-less than expected
• Preliminary photon testing shows good energy resolution
• Higher Voltage Gain than expected
Conclusions
• Data collection at 10kHz, given sufficiently fast support electronics
• Good frequency for current particle accelerators
Future Plans
• PPAC detector system
• Updated version of Stanford Linear Accelerator Center
• Use at CERN
Future Plans
• Multi-pixelated PPAC
Special Thanks To:
• Professor Yasar Onel
• Professor Edwin Norbeck
• Jonathan Olson
• All SSTP staff and students
• Will Swain
• Fermi National Accelerator Laboratory