Data Analysis of F2 and R in Deuterium and Nuclei

Vahe Mamyan, Hall-C collaboration meeting, January 18-19

Data Analysis of F2 and R in Deuterium and Nuclei

Physics

Experiment Setup

HMS Detectors

Calibrations

Data Analysis

Cross Section calculation

Vahe Mamyan

Ibrahim AlbayrakHampton University

Vahe Mamyan, January 2008 Hall C Users Meeting

Measurement of Measurement of R = R = LL / / TT on Deuterium in the on Deuterium in the

Nucleon Resonance RegionNucleon Resonance Region..

Physics


InclusiveInclusive e + d e + X ScatteringScattering

)(' LT

dEd

d

Where: = flux of transversely polarized virtual photons = relative longitudinal flux

12xF

FR L

T

L

122

22

2)4

1( xFFQ

xMFL

longitudinallongitudinal

TransverseTransverse

mmIIxxEEdd

Rosenbluth Separation Technique:


JAN05 ROSEN07

New data with high Q^2 above 3And new epsilon points for LT

separation


Physics

FL, F1, F2 Fundamental Structure Function Measurements on Deuterium

Structure Function Moments Lattice QCD comparisons Singlet and non-singlet distribution functions

Support Broad Range of Deuteron Physics Elastic form factors Spin structure functions Structure functions from deuterium cross sections

BONUS neutron structure functions Important input for neutrino physics Quark-hadron duality studies


FL can probe the gluon distributions…..

• Nucleon structure Nucleon structure composed of singlet composed of singlet (gluons, sea) and non-(gluons, sea) and non-singlet (valence) singlet (valence) distributionsdistributions

• At moderate x (~ 0.3), At moderate x (~ 0.3), singlet comparable to non-singlet comparable to non-singletsinglet

11


∫(Fd – 2Fp)dx yields non-singlet distribution

• The non-singlet moments can only be determined The non-singlet moments can only be determined from from differencesdifferences of proton and neutron moments. of proton and neutron moments.• Assuming a charge-symmetric sea, n-p isolates Assuming a charge-symmetric sea, n-p isolates the non-singletthe non-singlet• Need to pin down non-singlet (n-p) to extract Need to pin down non-singlet (n-p) to extract singlet (Fsinglet (FLL))• OPEN QUESTION IN QCD: Do we have valence, or OPEN QUESTION IN QCD: Do we have valence, or intrinsic, glue? Need Fintrinsic, glue? Need FLL

dd – 2F – 2FLLpp

““..highly precise deuteron data - due to the ..highly precise deuteron data - due to the above aspects -above aspects -are forming a conditio sine qua non for any real are forming a conditio sine qua non for any real precision test of QCD.” – Johannes Bluemleinprecision test of QCD.” – Johannes Bluemlein


Moments of the Structure Functions

Mn(Q2) = ∫dx xn-2F(x,Q2)

Calculated on the lattice at Q2 = 4 GeV2

Well understood in QCD Operator Product Expansion

0

1


Preliminary cross section for Deuterium…


Data to Monte Carlo simulation comparisons…


In Conclusion…

• No L/T separated resonance region (large x) data on deuterium currently

• Impossible to extract high precision moments

• Compare to lattice

• FL to access singlet


Experimental Setup

e-

e´-

Electron Beam

Target Scattering Chamber

HMS

X

Detector Hut

XeAe '


HMS Detectors

Drift Chambers,Horizontal and vertical

Vertically and Horizontally segmented hodoscopes

Gas Cerenkov Electro-magnetic calorimeter


Calibrations

BCM calibration A new BCM calibration script is written based on

C++/ROOT.

Drift Chamber and TOF calibration The calibration is done by one command, just run a batch

job and result is ready, quality is checked by examining the PS files produced after calibration.

Calorimeter calibration Gas Cerenkov calibration


BCM calibration


BCM calibration-cont.


Calorimeter calibration


Gas Cerenkov calibration


Data Analysis

Particle identification Background subtraction Acceptance calculation Corrections Cross section calculation


Particle Identification

Most background come from negative pions.

Calorimeter and Gas Cerenkov are used to reject these

pions.

HMS

P=0.44 GeV,

Θ=75 degree

Rejection factor is

100:1.8


Background subtraction

Electrons produced from charge-symmetric

πo and γ production and decay are background

for us. For this purpose special runs are taken

with HMS at positive polarity.

Since the background is charge-symmetric, it

allows to count the number of positrons and

subtract it from our data.


Acceptance calculation

Acceptance is calculated for each Θ-W2 bin. Number of Θ bins is fixed, 20 bins. Size of the W bin is 0.04 GeV2.


Corrections

Target boiling.

Radiative corrections.


Cross Section calculation

Avtgt NLLTEffNeWAccep

'NePS

dWd

W,d

22

22

bornelradallradelradmeascorr ___

i

ji

ijiji

jo

WBC

WBCWd

dWd

Wd

),(

),(,,

2

222

2

22

2_

2_

2 ,,, jiallradjoallradji WWWBC

Measured CS

Rad. corrected CS

Bin correction factor

Bin corrected cross section


Cross Section

No charge symmetric background subtracted


Summary

Calibrations are mostly done. Implement charge symmetric background

subtraction. Continue data analysis

Documents

Data Analysis of F2 and R in Deuterium and Nuclei