Experiment Rosen07: Measurement of Experiment Rosen07: Measurement of R = R = LL / / TT on Deuterium in the Nucleon on Deuterium in the Nucleon
Resonance Region.Resonance Region.
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Physics
Data Analysis
Cross Section calculation
L/T Separations
Ibrahim H. AlbayrakHampton University
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ROSEN07 (E06-009) is the second phase of the experiment JAN05(E04-001) with higher Q2 data.
ROSEN07 is combination of two experiments:Measurement ofMeasurement of R = R = LL / / TT on Deuterium in the Nucleon Resonance Region. on Deuterium in the Nucleon Resonance Region.
(I.Albayrak)(I.Albayrak)Measurement ofMeasurement of R = R = LL / / TT on Nuclear targets in the Nucleon Resonance on Nuclear targets in the Nucleon Resonance
Region.(Vahe Mamyan)Region.(Vahe Mamyan)
JAN05 is combination of two experiments:Measurement ofMeasurement of R = R = LL / / TT on Deuterium in the Nucleon Resonance Region. on Deuterium in the Nucleon Resonance Region.
(Ya Li)(Ya Li)Measurement ofMeasurement of R = R = LL / / TT on Nuclear targets in the Nucleon Resonance on Nuclear targets in the Nucleon Resonance
Region.(Ya Li)Region.(Ya Li)
ROSEN07 and JAN05 experiments
FL, F1, F2 and R fundamental Structure Function Measurements on Deuterium.
- These structure functions provide us important information about internal structure of nucleon, i. e. distribution of quarks and gluons inside the nucleus.
Since these are fundamental measurements, they allow a variety of physics issues to be addressed, such as:
– Structure Function Moments Lattice QCD comparisons Singlet and non-singlet distribution functions
– Quark-hadron duality studies– Neutron form factors.
– Support Broad Range of Deuteron Physics Spin structure functions BONUS (BOund NUcleon Structure) neutron structure functions
- Hall B experiment for NEUTRON cross sections via spectator tagging.
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Physics
Physics Motivation
Structure functions (F1 and F2) which have the Information of the nucleon’s internal structure.
Physics of Interest (Nucleon Structure)
Calculable in Quantum Electrodynamics (QED) {
Physics
Structure Functions: F1, F2, FL
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)(' LT
dEd
d
Where: = flux of transversely polarized virtual photons = relative longitudinal flux
12xF
FR L
T
L
Rosenbluth Separation Technique:
Physics
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)4
1/()2(2
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12 Q
xMxFFF L
longitudinallongitudinal
TransverseTransverse12xF
F
T
LL
• The non-singlet moments can only be determined from The non-singlet moments can only be determined from differencesdifferences of of proton and neutron moments.proton and neutron moments.• Assuming a charge-symmetric sea, n-p isolates the non-singletAssuming a charge-symmetric sea, n-p isolates the non-singlet
•Where Where
• Need to pin down non-singlet (n-p) to extract singlet .Need to pin down non-singlet (n-p) to extract singlet .
Md – 2Mp = ∫xn-2 (Fd ∙ f – 2Fp)dx yields non-singlet distribution
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Physics
Moments of the Structure Functions
Moments Calculated on the lattice at Q2 = 4 GeV2
Mn(Q2) = ∫dx xn-
2F(x,Q2)Mn(Q2) = ∫dx xn-
2F(x,Q2)
JAN05 ROSEN07
New data with higher Q2 And new epsilon points for LT separation
Physics
ROSEN07 experiment is the second phase of this experiment, the first phase was JAN05 experiment…
Purely New data with high Q2 above 3 GeV
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Current Status and Update Detector Calibrations Kinematic Corrections Dead Times Efficiencies Background Estimation and Subtraction: Target Density Correction Acceptance Corrections Bin-centering corrections Radiative corrections Iteration Procedure Systematic Uncertainties Extracting Differential Cross Sections Doing Rosenbluth L/T Separation Moment extraction N-p analysis
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Experiment & Data analysis
Data to Monte Carlo simulation comparisons…
Experiment & Data analysis
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Experiment & Data analysis
Drift Chamber Positions Offsets
Checked optics elements, magnets fields, matrix elements and no difference found from previous data.
Significantly different from previous data!!!
Could it be because of DC offsets?
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Drift Chamber Positions Offsets X direction
Experiment & Data analysis
Without X pos offset
Peak gets wider with any x offset
Must be Straight. Gets tilted with any x offset
No DC offset in X (vertical) direction!
For drift chamber position offset study I studied the width of the Elastic peak and Xptar. The narrowest the peak the best the position. XpTar plots should not be correlated with DC positioning.
With X pos offset
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Drift Chamber Positions Offsets Y Direction
Experiment & Data analysis
Ytar plot for Carbon target should be narrowest with correct positions
Peak gets narrower
Slope of the valley gives the best Y offset!
With Y pos offset
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Without Y pos offset
There is about 0.45 mm relative offset (distance)
between the DCs
Offsets for Drift Chamber Positions
Experiment & Data analysis
Before After
After correction y pos gets narrow, which indicates that we are doing the right thing.
After putting the relative offset 0.45 mm for Y position we get better comparison!
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Target Position Study (Again)
Experiment & Data analysis
After getting correct position information for Drift Chambers, Target position study needed to be redone.
C -0.105 0.0928 D2 -0.0665 0.0382Al -0.116 0.173 Fe -0.0861 0.0972 Cu -0.0764 0.0749
Del X
(cm)
Del Z
(cm)
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)tan()cos(
XZYY MCData
Experiment & Data analysis
Two simulation runs compared with and without radiative corrections to get the radiative effect on peak position.
Elastic Study (Kinematic Corrections)
And correct elastic peak position calculated after subtracting the radiative effect.
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Experiment & Data analysis
There is not enough data to do a precise kinematic offset study!
Elastic Study (Kinematic Corrections)
Two Photon experiment has enough number of elastic H data. They could
provide more precise results.16
E
EE
E
EEWWW protondata
A possible 0.3 mrad Theta offset. On average it gives
better results.
All this data is consistent with very small (> 10-4 ) E and E’ offsets
Experiment & Data analysis
Monte Carlo ratio method is used to extract data cross sections:
We can simulate Monte Carlo data using a cross section model to obtain
YMC
(E',q) = L* mod*( E W)*AMC
(E',q)
Taking ratio to data and assuming that AMC
= A, yields
d/dWdE' = mod * (Y(E',q)/Y
MC(E',q)) (MC ratio method)
Cross Sections Extraction Method
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Peter Bosted’s model used as input model. And this data has helped in the development of this model.
Experiment & Data analysis
Cross Sections (preliminary)
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And L/T Separations…
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Experiment & Data analysis
Here is some almost final rosenbluth separation plots for 2 different W2,Q2 pairs
)1/(
)1(
D
DA
DT
AT
D
A
R
RRr
r
Advantage of this method: Systematic errors cancel.
And L/T Separations…
Plots of R ,first one have Q2 range 0.5-2.25 second one Q2 range 2.25-4.5 for Carbon.
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Experiment & Data analysis
Summary
Calibrations are done. Charge symmetric background subtraction,
radiative corrections and other corrections are mostly done.
Some L/T separations have already been done (Vahe).
Continue data analysis L/T separations Moment extractions n-p analysis21
Experiment & Data analysis