Physics Data Analysis Cross Section calculation L/T Separations

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…


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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


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


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


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)


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


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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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


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.


Cross Sections (preliminary)

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And L/T Separations…

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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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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


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Physics Data Analysis Cross Section calculation L/T Separations