Experiment Rosen07: Measurement of R = sL / sT on Deuterium in the Nucleon Resonance Region.

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Experiment Rosen07 Measurement of R sL / sT
on Deuterium in the Nucleon Resonance Region.

• Physics
• Experiment Setup
• HMS Detectors
• Calibrations
• Data Analysis
• Cross Section calculation

Ibrahim H. Albayrak
Hampton University
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Physics
Structure Functions F1, F2, FL

Structure functions (F1 and F2) which have the
Information of the nucleons internal structure.
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Physics
Rosenbluth Separation Technique
Where ? flux of transversely polarized
virtual photons ? relative longitudinal flux
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Physics
Physics Motivation

• 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
• Singlet and non-singlet distribution functions
• Lattice QCD comparisons
• 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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FL, F1 , F2 structure functions
Physics
F1 is transverse structure function
F2 is mixed structure function

• describes the momentum distribution of the
  quarks inside the nucleon.

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?(Fd 2Fp)dx yields non-singlet distribution
Physics
This Data Provides Constraints on Gluon
Distributions in two Ways
1- FL can probe the gluon distributions..
FL(x,Q2) (as(Q)/2p)x2 ? dy/y3 8/3F2(y,Q2)
2?ei2(y-x)g(y,Q2)
2- n-p provides non-singlet and therefore singlet

• Nucleon structure composed of singlet (gluons,
  sea) and non-singlet (valence) distributions
• At moderate x ( 0.3), singlet comparable to
  non-singlet
• gt Singlet and non-singlet separation provides
  extra constraint on gluon distribution.

• The non-singlet moments can only be determined
  from differences of proton and neutron moments.
• Assuming a charge-symmetric sea, n-p isolates
  the non-singlet
• Need to pin down non-singlet (n-p) to extract
  singlet .

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Physics
Moments of the Structure Functions
Mn(Q2) ?dx xn-2F(x,Q2)
Moments Calculated on the lattice at Q2 4
GeV2 For proton, n 2 F2 moment 0.182 /-
0.006 For deuteron, n2 F2 moment / nucleon
0.165 /- 0.008 Since Lattice calculates only
valence quarks, singlet/non-singlet separation
allows for precise Lattice comparisons.
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Deuteron, Neutron, and non-singlet L/T Moments
Physics
- Can extract low Q2 neutron moments with
minimal uncertainties from nuclear
corrections! - Below x lt 0.7 is the safe region
to extract neutron moments because nuclear
corrections are small in this region. - Neutron
L/T SFs can be extracted using proton and
deuteron L/T SFs combined with BoNuS neutron
cross sections.
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Physics
New data with high Q2 above 3 GeV And new epsilon
points for LT separation
ROSEN07
JAN05
ROSEN07 experiment is the second phase of this
experiment, the first phase was JAN05 experiment
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Current Status and Update
Experiment Data analysis

• Detector Calibration Completed
• Calorimeter Eff. Completed
• Cerenkov Eff. Completed
• Tracking Eff. Detailed study in progress
• Trigger Eff. Detailed study in
  progress
• Computer Dead Time Detailed study in
  progress
• Acceptance Corrections Needs to be redone
• Beam Position Stability Study Completed
• Beam Position Offsets Needs to be redone
• Target Position Offsets Needs to be
  redone
• Optics Checks Preliminary Checks
• Charge Symmetric Background Completed
• Radiative Corrections Iterating
• Cross Sections Iterating

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Experiment Data analysis
Charge Symmetric Background Subtraction(From
Vahe)
Cross Section(CS) fit function has exponential
form, with constraint CS0 at EEbeam.
Cross section is interpolated by a polynomial in
theta and used in CSB subtraction.
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Experiment Data analysis
Cerenkov Center Efficiency Correction
This effect is bigger than we had in Jan05. That
might be because cerenkov had been moved between
the two experiments.
Due to the gap between the cerenkov mirrors,
there is an efficiency problem in the center
region.
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Experiment Data analysis
Cerenkov Center Efficiency Correction
Before the correction
After the correction
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Experiment Data analysis
Data to Monte Carlo simulation comparisons
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Experiment Data analysis
Preliminary Drift Chamber Position Studies
Significantly different from previous data!!!
Checked optics elements, magnets fields, matrix
elements and no difference found from previous
data.
FPP was tested before ROSEN07. Would detector
positions have been effected by all that weight
on detector frame?
Could it be because of DC offsets?
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Experiment Data analysis
Preliminary Drift Chamber Position Studies
Center pos of Jan05 data
Dx_DC10.70cm
Dx_DC20.45 cm
Center pos of ROSEN07 data
Dy_DC10.33 cm
Dx
Dy_DC20.30 cm
ROSEN07
Mean 0.34
x and y positions of drift chambers of old
(Jan05) and new (Rosen07) data compared to find
the amount of shift.
Mean 0.01
JAN05
Dy
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Experiment Data analysis
Preliminary Drift Chamber Position Studies
Point target study 1 RL Carbon target
Before
After
After DC position adjustment in replay 1-Y/ tar
comparison gets better, 2- Ytar becomes
narrower,
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Cross Sections Extraction Method
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 smod( DE DW)AMC(E',q) Taking
ratio to data and assuming that AMC A, yields
ds/dWdE' smod (Y(E',q)/YMC(E',q))
(MC ratio method)
Peter Bosteds model used as input model. And
this data has helped in the development of this
model.
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Cross Sections (preliminary)
Experiment Data analysis
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Cross Sections (preliminary)
Experiment Data analysis
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And L/T Separations
Experiment Data analysis

• Here is some preliminary L/T separations from
  Vahe Mamyan.

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Summary
Experiment Data analysis

• Calibrations are done.
• Charge symmetric background subtraction,
  radiative corrections and other corrections are
  mostly done.
• Some preliminary L/T separations have already
  been done (Vahe).
• Continue data analysis
• L/T separations
• Moment extractions
• n-p analysis