Hall-C Coincidence

Commissioning Experiments

E12-10-104 & E12-10-003 Krishna Adhikari

Mississippi State University

1 Joint Hall-A & Hall-C Summer meeting

(July 17-18, 2015)

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E12-10-104: Theoretical Motivation

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Hadron Propagation & Transparency

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• Measurement of proton and pion transparencies will provide an

understanding of the propagation of highly energetic particles

through the nuclear matter.

• The A(e,e’p) process will provide valuable information on the

interpretation of the rise in transparency found in the BNL

A(p,2p) experiments. This is true even if these experiments do not

find a rise in transparency in the Q2 range covered. There is

large overlap with the beam momentum range of the BNL

experiment.

• The A(e,e’π+ ) process can map the region in Q2 from the onset

of CT to ~10 GeV2, where such effects validate the strict

applicability of factorization theorems for meson electro-

production experiments.

Hadron Propagation & Transparency

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• Hadron propagation through the nuclear medium is a

key element of the nuclear many body problem.

• Understanding hadron propagation is important for

the interpretation of many phenomena and

experiments, and remains an active area of interest. – N. C. R. Makins et al. PRL 72, 1986 (1994) (cited 153 times)

– G. Garino et al. PRC 45, 780 (1992) (cited 88 times)

– D. Abbott et al. PRL 80, 5072 (1998) (cited 88 times)

– K. Garrow et al. PRC 66, 044613 (2002) (cited 92 times)

• At high energies the main process is reduction of flux,

which is called Nuclear Transparency.

• Nuclear transparency can also be used to search of

signature of QCD in Nuclei.

Nuclear Transparency

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Nuclear Transparency

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For light nuclei very precise calculations are possible.

Nuclear Transparency

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Color Transparency: a color coherence

property of QCD

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Color Transparency: a color coherence

property of QCD

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First direct search for color transparency

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Current Status of CT (Search for the onset of CT )

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A(e,e’p) @ 11 GeV JLab

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E12-10-104: Hadron Propagation & Color

Transparency at 12 GeV

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Total beam time requested for A(e,e’p) is ~10 days (for 10 cm LH2)

Spokespersons: D. Dutta & R. Ent

E12-10-104: As a Commissioning Expt.

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E12-10-104: As a Commissioning Expt.

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• SHMS used as hadron arm

(modest requirements)

– A(e,e'p) needs p/π separation

– Singles rates < 10kHz

– p/π ratio 1:1 - 1:2

• Targets needed:

– 10 cm LH2

– thick and thin Carbon.

– 4 cm LH2 & multi-foil for

commissioning

spectrometer

SHMS & Target requirements

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Commissioning Run Plan

Projected results

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Next Experiment

E12-10-003

Deuteron Electro-Disintegration at Very

High Missing Momenta (E12-10-003)

K. Aniol,1 A. Asaturyan,2 H. Baghdasaryan,3 F. Benmokhtar,4 H. Bitao,5 W.U. Boeglin (spokesperson),6 S. Danagoulian,7 D. Day,3 D.

Gaskell,8 D. Higinbotham,8 G. Huber,9 S. Jeschonnek,10 X. Jiang,11 M. K. Jones (co-spokesperson),8 N. Kalantarians,3 C. Keppel,12 M.

Kohl,12 P.E. Markowitz,6 A. Mkrtchyan,2 H. Mkrtchyan,2 E. Piasetzky,13 A. Puckett,11 B.A. Raue,6 J. Reinhold,6 G. Ron,13 M. Sargsian,6

R. Shneor,13 G. Smith,8 R. Subedi,3 V. Tadevosyan,2 J. W. Van Orden,14 F. R. Wesselmann,15 S. Wood,8 and S. Zhamkochyan2

(1)California State University L.A., (2) Yerevan Physics Institute, (3) University of Virginia, (4) Carnegie Mellon University, (5) Lanzhou University, (6) Florida

International University, (7)North Carolina A&T State University, (8) Jefferson Lab, () 9University of Regina, (10) Ohio State University, (11) Los Alamos

National Laboratory, (12) Hampton University, (13) Tel-Aviv University, (14) Old Dominion University, (15) Xavier University of Louisiana

D(e,e’p)n with the neutron

missing mass and angle

reconstructed

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Previous Hall A experiment (E01-020)

• Data taken for d(e,e’p)n reaction with cut on neutron

reconstructed missing mass at Q2 = 3.25 GeV2.

Published in PRL 107, 262501

• Top plot is ratio of measured cross section to the

predicted PWIA cross section versus qnq for 3 bins of

missing momentum: pm = 200,400 and 500 MeV/c

o pm = 200 data has dip at qnq = 70-80o

o pm = 400 and 500 show peak at qnq= 70-80o due to

large FSI with larger FSI for high pm

o All pm bins have small FSI at qnq = 40o±10

• Bottom plot is the reduced cross section plotted versus

pm for bins of qnq = 35o±5 (blue points) and qnq = 75o±5

(red points)

• In the PWIA , the reduced cross section maps the

deuteron wave function. The lines are PWIA

calculations using the CD Bonn and Argonne V18

deuteron wave functions.

• qnq = 75o±5 shows large FSI for pm > 350

• qnq = 35o±5 data is in good agreement with PWIA

calculations and indicate that measurements at

these kinematics will be sensitive to deuteron wave

function.

• Would like data at higher missing momentum!

200 400

Pm = 500

Large FSI

Pm dependent

qnq = 75o

qnq = 35o

The experiment will: Determine cross sections at missing momenta above 0.5 GeV/c

Measure at well defined kinematic settings at Q2 = 4.25

– Selected kinematics to minimize contributions from FSI

– Selected kinematics to minimize effects of delta excitation

Motivation: – Explore a new kinematical region of the 2-nucleon system above pm> 500

– No Deuteron data exist at these kinematics!

– Short range correlation studies cover similar region on missing momenta

– DIS at high Q2 and small x and J/Y production are sensitive to Deuteron

wave function at small distances

– Models are able to reproduce the present data.

Experimental Goals

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Experimental Setup

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Beam:

Energy: 11 GeV

Current: 80mA

Electron arm fixed at: SHMS at pcen = 9.32 GeV/c

qe = 11.68o Q2 = 4.25 (GeV/c)2

x = 1.35 qnq = 40o

Vary proton arm to measure: HMS 1.96 ≤ pcen ≤ 2.3 geV/c

Angles: 63.5o ≥ qp ≥ 53.1

pm = 0.5, 0.65, 0.8 GeV/c

Kinematics and Beam Time

0.2 0.4 0.6 0.8 1.0 1.2 1.4

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30

40

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pm (GeV/ c)

Cou

nts

(I)

(II)

(III)

I. pm = 0.5 (GeV/c), beam time 8 hours

II. pm = 0.65 (GeV/c), beam time 18 hours

III. pm = 0.8 (GeV/c), beam time 36 hours

Beam:

Energy: 11 GeV

Current: 80mA

Electron arm fixed at:

SHMS at pcen = 9.32 GeV/c

qe = 11.68o Q2 = 4.25 (GeV/c)2

x = 1.35 qnq = 40o

Vary proton arm to measure :

pm = 0.5, 0.65, 0.8 GeV/c

HMS 1.96 ≤ pcen ≤ 2.3 geV/c

Angles: 63.5o ≥ qp ≥ 53.1

Detect electron and proton and reconstruct missing mass of neutron.

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Expected Results

Total beam time : 62 Hours

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Summary

• Two coincidence commissioning experiments for Hall-C

• E12-10-104: A(e,e’p) data to study high energy proton

propagation in nuclear matter (nuclear transparency) and

color transparency (CT)

• E12-10-003: New Deuteron data in unknown kinematic

territory

• Modest requirement on precision

• PID:

e/p separation with Cherenkov and calorimeter

p identification with coincidence timing

• Data can be produced while performing spectrometer

commissioning

• Experience gained during this experiment will help later

experiments that require higher precision 27

Thank you!!!

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