Post on 03-Jan-2016
Measurementof Gas Bremsstrahlung
at the Pohang Light Source
Hyosang LeeSeoul National University, Q2C
Pusan National University, HANUL
HNP2011
Contents
Measurement of gas bremsstrahlung
Measurement of hadron photoproduction
MotivationPohang Light Source (PLS)
3rd generation synchrotron facility with a beam emittance of 18.9nm⋅rad
2.5GeV electron linear accelerator : full energy injector for the storage ring
2.5GeV Electron Storage Ring: 12-period Triple Bend Achromat lattice
180mA at 2.5GeV
Design to provide synchrotron radiation with continuous wavelengths down to 1Å
LINAC
Storage Ring
MotivationBremsstrahlung
produced through electromagnetic interactions of circulating electrons
with storage ring components
with residual gas in vacuum
carrying polarization information of the electrons circulating
time evolution of the electron polarization(due to spin-flip synchrotron radiation) -> electron energy
measurement of gas bremsstrahlung = measurement of electron energy
Eγ = 0 ∼ Emax,e-
First gas bremsstrahlung measurement at PLS
Experimental method3 data taking run : 2007, 2009, 2010
Detector : scintillation crystal [CeF3, PbWO4, CsI]
1C1 beam line
straight section with 5.3 m
vacuum : 0.5nTorr
photon transport : 6.3ϕ, 13.6m
soft-X ray shielding : 2mm Pb slabs
componentcomponent Mole fraction(%)Mole fraction(%) Weight fraction(%)Weight fraction(%)
H2 90 41.86
N2/CO 5 32.55
CH4 3 11.16
CO2 1 10.23
H2O 1 4.18
Experimental method
CeF3
PbWO4CsI
Detector : CeF3, PbWO4, CsI
Tungsten collimator : ϕ3, 7mm
veto by plastic scinti. to reject e+e-
Beam profile - 2007 data
tungsten wire + 1x1mm2 scinti.
CeF3
x-axis : 10mm
y-axis : 4mm
Raw data & Energy Calibrationcenter CeF3 : ~78% (MC 77.6%)
1/Eγ distribution
Geant4 simulation center - 77.6% surrounding - 19.4% leakage - 3%
Energy calibration
Result - 2007 data
photon flux - 10/s @ >400MeV with 180mA - 39/s @ 180mA
Energy resolution -
Experimental setup - 2009
Detector PbWO4 : 1.9cm x 1.9cm x 20cm CsI : 7cm x 7cm x 30cm
5B1 beam line with 5.3 m straight line
PWO centerPWO sumTotal sumCeF3 sum
Result - 2009
Result - 2009
Need energy calibration with fixed energy beam
CsI energy
PWO energy
Energy sum
??
Hadron photoproduction - motivation
Hadron photoproduction : 0.23 Hz
By using gas bremsstrahlung
γp -> π0p
πp
Hadron photoproduction - Experiment3x3 PWO
5x5 CsITarget & Start Count
to measurebremsstrahlu
ng
to measureπ0->γγ
Measurement of bremsstrahlung
Measurement of hadron photoproduction with γp->π0p
Experimental setup
start time
ToFto measure p
Beam
γp -> π0p
Hadron photoproduction - SignalUpveto Start Counter
Multiplicity in ToF ToF
Hadron photoproduction - ToF Calibration
t0 calibration
time correction
position calculation
Hadron photoproduction - CsI Calibration
CsI calibration with cosmic-ray muon
Hadron photoproduction - γ clustering
Geant4 simulationreal data
clustering method
No π0 events ?
Next to do : - γ hit position - energy leakage - energy calibration
No π0 events ?
Next to do : - γ hit position - energy leakage - energy calibration
Hadron photoproduction - π0 mass
real data
Geant4 simulationCeF3 Energy
Hadron photoproduction - Dipole Magnet
Hadron photoproduction - Dipole Magnet
SummaryMeasurement of Gas Bremsstrahlung
First measurement
3 data run
Detector : CeF3, PbWO4, CsI
photon flux - 10/s @ >400MeV with 180mA - 39/s @ 180mA
Need to energy calibration with fixed energy beam
Measurement of Hadron
Hadron photoproduction : 0.23 Hz
By using gas bremsstrahlung
γp -> π0p