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Elastic Electron Scattering off He and He (E04-018) Elena Khrosinkova Kent State University Hall A Collaboration Meeting Jefferson Lab, June 2008 3 4
Transcript of hallaweb.jlab.orghallaweb.jlab.org/collab/meeting/2008-summer/talks/Khrosinkova_He… · Title:...
Elastic Electron Scattering off
He and He (E04-018)
Elena Khrosinkova
Kent State University
Hall A Collaboration Meeting
Jefferson Lab, June 2008
3 4
Objective
Elastic scattering off helium's stable isotopes at
large momentum transfers
Extraction of He3 charge and magnetic and He4
charge form factors
3
Jefferson Lab, June 2008 2/17
Experimental Apparatus
Coincidence experiment using TOF method
20 cm helium cells
Jefferson Lab, June 2008 3/17
Elastic Electron-Helium Scattering
He charge and magnetic form factors:
,
He charge form factor:
2sin
2cos
2sin4
' 2222
43
22
E
EZ
d
dA B
2Q const
1
22222
2QFQF
QMC
22222 QFQ
MA B
22
43
222
2sin4
2cos'
QF
E
EZ
d
dC
3
4
Jefferson Lab, June 2008 4/17
2sin4
22EEQ
Data range
Jefferson Lab, June 2008 5/17
Data range
Jefferson Lab, June 2008 6/16
Data range
Jefferson Lab, June 2008 7/17
Analysis projects
Current Calibration
2 current calibrations
Normalization of the current
at the injector cavity to the
Faraday cup
Cross-check with the Unser
current
Jefferson Lab, June 2008 8/17
Normalization of the
two BCM cavities to
the calibrated injector
cavity
Analysis projects
Current Calibration
Jefferson Lab, June 2008 9/17
Normalization of the
scalers frequency
(right, left) to the
average value of the
calibrated injector
cavity current
Analysis projects
Current Calibration
Jefferson Lab, June 2008 10/17
Analysis projects
Calorimeter calibration
6x6 blocks
calibration
MC simulation for
energy deposited in first
and second layers
1222 – 1273 runs
ep elastic, 2.13 GeV
E/p vs E
E/p
Co
un
ts
Jefferson Lab, June 2008 11/17
Cerenkov sum corrected
Analysis projects
Cerenkov Gain Equalization
With cuts on >99% of total
light in one particular tube
Number of photoelectrons > 6
Cerenkov efficiency
close to 100%
1222 – 1273 runs
ep elastic, 2.13 GeV
7.9N
L.cer.a_p[4]
L.cer.a_p[5]C
ou
nts
1.9N
7.9N
Jefferson Lab, June 2008 12/17
Analysis projects
Timing Offsets Correction
1232 – 1233 runs,
ep elastic
2.34 GeV
Jefferson Lab, June 2008 13/17
tof, uncorrected
tof, corrected
Cou
nts
Cou
nts
Analysis projects
Scintillators ADC Equalization
L.s1.ra_p[3]
L.s1.ra_p[2]
L.s1.la_p[3]
L.s1.la_p[2]
L.s1.la_c[*] + L.s1.ra_c[*]
Jefferson Lab, June 2008 14/17
1222 – 1273 runs
ep elastic, 2.13 GeV
Analysis projects
Event Display
Jefferson Lab, June 2008 15/17
3D event display
For all tracks from the analyzer
LHRS and RHRS
Cuts for “fired” blocks
In progress
Elastic stripe
= 40 fm , e He2Q
2 3
Jefferson Lab, June 2008 16/17
Left, m
Summary
Finalization of the detector calibrations
Improving tracking routine
Ready for mass analysis
Jefferson Lab, June 2008 17/17
