Data Analysis (ODU) and Simulations (J. Udias, Madrid)

Outline• Introduction

– Hall A and Electron Scattering

• Experiment

– Goals and Kinematics Setup

• Data Analysis

– Good Runs, Target Foils, TOF, Acceptance

– Comparing to Previous Work

– R-Function and Results

•Summary and What’s Next?

HallHall A A

TargetTarget

HRS-L HRS-R

HRS = High ResolutionSpectrometer

Mom Resolution Mom Accpt

1 x 10-4

± 4.5%

Solid Angle 6 msr

Angular Range(in degree)

12.5 – 150 (L)12.5 – 130 (R)

Angular Accpt ± 30 mr (ver)± 60 mr (hor)

Angular Resolution

1 mr ( ver)0.5 mr (hor)

TOF Resolution 1 ns FWHM

dd

Electron-Nucleus Interactions

Three cases: Low q

– Photon wavelength larger than the nucleon size (RN)

Medium q: 0.2 < q < 1 GeV/c ~ RN

– Nucleons resolvable High q: q > 1 GeV/c

< RN

– Nucleon structure resolvable

Select spatial resolution and excitation energy independently• Photon energy determines excitation energy• Photon momentum q determines spatial resolution hbar/q

Energy vs Spatial Resolution

Diagram of A(e,e’p)

Missing Energy:

Missing Momentum:

Em = - Tp – TR

pm = q – p’

4-vector transferred mom:

Invariant :

Q2 = 4EiEf sin2(e/2)

Outline

• Introduction– Hall A and Electron Scattering

• Experiment– Goals and Kinematics Setup

• Data Analysis– Good Runs, Target Foils, TOF, Acceptance– Comparing to Previous Work– R-Function and Results

• Summary and What’s Next?

Goals of E00102 Measurement of cross-section, RLT and ALT

for the 16O(e,e’p) reaction with higher precision and to higher missing momentum than in E89003.

Determine the limit of validity of the single-particle model of valence proton knock-out.

Determine effects of relativity and spinor distortion on valence proton knock-out using the diffractive character of the ALT symmetry.

Determine bound-state wave function and spectroscopic factors for valence proton knockout.

E00102 Setup

Ebeam = 4.620 GeV Mom central: 1.067 GeV/c (proton)

and 4.120 GeV/c (electron) Mom transfer, |q| = 1.073 GeV/c

Energy transfer, = 0.499 GeV Q2 = 0.902 (GeV/c)2

e = 12.50o (fixed) 28.3o < p < 96.2

o (+/- kins) 0 < Em < 0.240 GeV -0.515 < pm < 0.755 GeV/c

Kin Settings• 9 “Negative” Kins• 11 “Positive” Kins • 1 Parallel Kin

Statistics • Total : 1743 runs• Good (77%)• Fixable (4%) • Calibration (6%) • Bad Runs (13%)

E00102 Kinematics

+

mm

mm

28o – 96o

• Introduction– Hall A and Electron Scattering

• Experiment– Goals and Kinematics Setup

• Data Analysis– Good Runs, Target Foils, TOF,

Acceptance– Comparing to Previous Work– R-Function and Results

• Summary and What’s Next?

Outline

Good Runs

coll open

coll 6msr

Fixable

Bad Runs

T1/T3

RUNNO

T1 = Proton RatesT3 = Electron Rates

Determining “Good” Runs For Kin AA+

Uncut CTOF cut

How We Handle Targets Kin AA+

Foil 1

Foil 2

Foil 3

Time of Flight : Kin AA- (1531)

1 32

Region A

Missing Energy Spectra : Kin AA- (1531)

True = Real – 2 Accidental (1+ 3)

Events

1P1/2

1P3/2

Mistiming factor

1P1/2 Relative Cross SectionComparing to Previous Results*

• Determination of 1P1/2 cross section relative to H(e,e’)

* M. Anderson, Licentiate Thesis October 2005

Previous Work This Work

Pm Range

0 < Pm < 350 MeV Same

Kins A+, C+, D+, E+, F+ A± and D±

Bin Size Pm: 2 MeV/c (A-D) 4MeV/c (E-F)

Pm: 2 MeV/cEm: 0.5 MeV

Accpt cuts

: ±50 mr, : ±50 mr: ±3.5%

: ±50 mr, : ±25 mr: ±3.5%

Unc. 7% (stat) and 5%(syst) 7% (stat)

Only used central target foils !

Relative Cross Section• Cross Section :

16O(e,e’p) :

H(e,e’) :

• Relative Cross Section :

No L !

Data

• Replayed good runs • Implemented energy loss correction • Studied CTOF, zreact, acceptances, Emiss, Pmiss, mistiming factor correction, etc.

• Applied angular cuts : (±50 mr) and (±25 mr)

• Applied momentum cuts : (±3.5%)• Applied background subtraction.

Simulation

• Bound states physics models – calculated by Madrid Group.

• Spectrometer models – ON, radiative effects – ON, and energy loss correction – OFF

• Use the same acceptance values (,,and ) as in data.

• Use target configuration that built into the MCEEP.

Recipe relative for 1P1/2

1. Apply cuts on tg, tg, zreact, CTOF (Region A), and Emiss.

2. Subtract CTOF background bin-by-bin.

3. Apply mistiming correction factor4. Normalize to 1H(e,e’)luminosity5. Normalize to MC phase-space6. Divide each data point by pmiss

bin width

relative for 1P1/2 (Central

Foils)

Pmiss (MeV/c) dhfkjklll

Previous Work

Pmiss (MeV/c)

AA+

DD+

AA-

DD-

relative for 1P1/2 (Central

Foils) This Work

R-FunctionMaximize Event Acceptance

Determine nominal acceptance boundaries (tg, tg, ) for each HRS.

R-function measures distance (+/-) to boundary of each trajectory : 1. R < 0.0 outside 2. R >= 0.0 inside

Choose cut to make on R a. where we understand the acceptance b. Maximize it

tg

tg

R-arm Kin AA- (1531)

R-Functions of Kin AA+ (1315)

Red (Data) and Blue (Simulation)

L-Arm R-Arm

Where to R-Function Cuts? (Kin AA+)L-Arm R-Arm

Value of R-Function Cuts

Next plots four different conditions of R-cut are used:1. No R-cut (uncut)2. R > 0.03. R > 0.0054. R > 0.01

Uncut R > 0.0 R > 0.005 R > 0.01

L-Arm Acceptance with 3-foils : Kin AA+

R-Arm Acceptance with 3-foils : Kin AA+Uncut R > 0.0 R > 0.005 R > 0.01

Missing Momentum : Kin DD+ (1497)

R > 0.005 R > 0.01R > 0.01R > 0.005

R > 0.0Uncut

Outline

• Introduction– Hall A and Electron Scattering

• Experiment– Goals and Kinematics Setup

• Data Analysis– Good Runs, Target Foils, TOF, Acceptance– Comparing to Previous Work– R-Function and Results

• Summary and What’s Next?

Summary and What’s Next?

Intensive studies to understand both data and simulation has been performed. Treatment for both data and simulation is better understood.

All three foils cut would be used (previous work only used the central foils).

R-function is now better understood and will be implemented as the acceptance cut for both data and simulations.

Ready to replay to all different sets of kinematics and ready to fix/save runs (to gain better statistics).

Plan to perform the reduced cross section and make plots of red versus pmiss for available replayed runs in each kinematics.

THANK YOU,ANY QUESTION ?