Israeli Participation in

Heavy Ions and Fixed Target Experiments

(HE and Nuclear Physics)

Restricted ECFA meeting

Israeli Academy of Science, Jerusalem

Friday, 21 May 2005

E. Piasetzky

School of Physics and Astronomy

Tel Aviv University

• Scientific program and physics highlights.

Hardware Contributions.

People, group size, and activities.

Summary and overview.

Outline:

Period: 1990-2005

More information can be found in slides 37-80 which do not have time to present.

Experimental groups in Israel:

Relativistic heavy Ion:Relativistic heavy Ion:

1990-1999 NA45 / CERES at CERN

1999- NOW PHENIX / RHIC at BNL

Fixed Target particle physics experiments:

Experiments at Fermilab:

E 781 (SELEX)E 665

E 791

measurement of the pion valence – quark momentum distribution.

Search for particles made of 5 and 6 quarks.

Observation of Color-Transparency in Diffractive Dissociation of pions.

Double Charm Baryon Spectroscopy.

Polarization Measurement of the Lambda produced in Deep inelastic muon scattering.

COMPASS at CERN

NA-47 (SMC) at CERN

Determination of the gluon polarization.

Spin structure of the nucleon.

Π Polarisabilities via Primakof reaction.500-50 GeV

Scientific program

GeVSNN 200

GeVSNN 17

EVA at Brookhaven National Lab.

Study of hard proton induced reactions.

Measurement of short range correlation in nuclei.

E850 / EVA

Experiments at Jefferson Lab.

Measurement of the neutron charge FF: GEn

Measurement of short range correlation in nuclei.

Hard photo-disintegration of a pp pair.

E02-013, E93-0026

E01-015 E03-101

Mainz Microtron MAMIA2 collaboration

Measurement of the π+ polarizabilities.

TRIUMF: Measurements of pion integral cross sections for low and the 3,3 resonance energy regions.

PSI : Precision measurement of elastic scattering of low energy π+ , π- on nuclei.

Total π- p SCX cross sections between 40-240 MeV.

1-20 GeV

20-300 MeV

Scientific program

Radioactive nuclear beamsRadioactive nuclear beams

Measurements of ground-state magnetic moments of short-lived Mirror Nuclei.

ISOLDE / CERN

Precision measurement of the 7Be(p,gamma)8B cross section.

Parity non-conservation in 180mHf.( An experiment to be run in 2005).

Study of nuclear astrophysics reactions using ion beams.

SARAF (Soreq Applied Research Accelerator Facility)

TRIUMF Radioactive beam and Neutral Magneto-Optical atom Trap

Symmetry Tests in β Decay.

0-2 MeV

Scientific program

Main CERES Result: strong enhancement of low-mass dileptons hinting at Chiral Symmetry Restoration

Strong enhancement of low-mass e+e- pairs in A-A collisions(w.r.t. to expected yield from known sources)

No enhancement in p-Be and p-AuQuantitative explanation requires:thermal radiation from high-density

with in-medium modification of theintermediate meson hinting at

chiral symmetry restoration

Spectral shape broadening

HG +- * e+e-

dropping meson mass

hadron cocktail

free meson

physics highlights

Main PHENIX Results• discovery of jet quenching (suppression of high pT particles).

• very high energy density state (30-100 times dense than normal nuclear matter).

• rapid equilibration.

• strongly interacting system exhibiting collective behavior.

• suggestion of a perfect primordial fluid (almost zero viscosity), behaving more like a liquid, not as a gas.

d-Au

Au-Au

0 yield w.r.t. to pp collisions

The first PHENIX paper (PRL 86, 3500 (2001)) is based on an analysis of the WI group.

physics highlights

E 791 / FNAL : Direct measurement of the pion valence – quark momentum distribution

... ggqq gqq qqa The pion wave function can be expanded in terms of Fock states:

The valence (first) state with the minimal gluon content, very small size, large mass, is about 25% of the light cone wave function.Diffractive dissociation of 500 GeV/c π - into di-jets from a platinum target at FNAL exp 791 allows to measure the internal momentum distribution of the valence quarks in this state.

Q2~16(GeV/C)2Q2~8 (GeV/C)2

The light-cone asymptotic wave function describes the data well for Q2>10 (GeV/c)2.

physics highlights

SELEX, the charm hadro-production experiment (E781) at Fermilab opened a new horizon for charm baryon spectroscopy.

SELEX 4 double charm states .

physics highlights

First observation of the Doubly Charmed Baryon (3520) cc PRL 89 (2002) 112001

Confirmation via another decay mode:

Analysis done at TAU

Submitted to PRL ( hep-ex / 0406033)

SELEX : Kccc pKc

pKDcc KD

The two decay modes give consistent mass. The averaged mass is 3518±3 MeV/c2.

The relative branching ratio:

)()( KKpD cccccis

0.0450.078

physics highlights

How ΔG/G is measured

Photon-Gluon Fusion (PGF) G

GAPGF

N

ggG

ΔG/G from high pt hadron pair, Q2 > 1

ΔG/G = 0.06 ± 0.31stat. ± 0.06syst.

Open charm

cc

4%) (BR 0 KD

ccDD .0*

At this point only raw asymmetry is available.

Preliminary result based on 2002-2003 data.

q

q

N

physics highlights

Measurement of short range correlations in nuclei.E 01 - 015

The method:

To study nucleon pairs at close proximity and their contribution to the large momentum tail of nucleons in nuclei.

The goal:

“Redefined” the problem in momentum space

A pair with “large” relative momentum between the nucleons and small CM

momentum.

p

e

ep

n

HRSHRS

BigBite

n-array

Experimental setup:

physics highlights

Precision measurement of elastic scattering of 21.5 MeV π+, π- on Si, Ca, Ni, and Zr.

The Goal: Testing the “anomalous” s-wave repulsion as observed in pionic atoms.

Method: using the πE3 channel of PSI and the low energy pion spectrometer (LEPS).

Results:

The extra repulsion observed in pionic atoms data was confirmed by the scattering data.

In medium modified pion decay constant reconcile the π-nucleus and πN interactions.

This is consistent with a recent suggestion by Weise et al. using chiral restoration model.

PRL 93 (2004) 122302.

physics highlights

Hardware Contributions:

•All the gas detectors for CERES were designed,

constructed and operated by the WI group.

Double RICH spectrometer – no real tracking

Readout chambers of the two RICH detectors

CERES Spectrometer: 1992

CERES Spectrometer: 1995

Add tracking with a doublet of SiDC before, and a pad chamber after the double RICH spectrometer Add Pad Chamber

CERES Spectrometer: 1999

Improve tracking and mass resolution with a radial TPC

Readout chambers of the TPC PHENIX

Hardware Contributions

Essential components of the PHENIX particle tracking

system.

Composed of three layers of pixel detectors PC1, PC2

and PC3.

PC1 (design, construction, installation…) is the

responsibility of WI group.

Hardware Contributions:

A sector of PC1 mounted on the drift chamber and ready to be installed on the PHENIX central arm (photo taken in 9/99).

Pad Chambers

Hardware Contributions:

Design construction and operation of HBDHadron Blind Detector for PHENIX

♣ windowless Cherenkov detector (L=50cm)

♣ CF4 as radiator and detector gas

♣ CsI reflective photocathode

♣ Proximity focus: detect blob not ring

♣ Triple GEM with pad readout

HBD concept

Final HBD design

Detectors built by the experimental group at Tel Aviv University are moved to be installed in the experimental Hall A of the Jefferson Lab.

Dec. 2004

The n-array

Scintillator hodoscopes for the BigBite spectrometer

Hardware Contributions:

ISOLDE + Tilted-foil polarization + HV Platform + β NMR

60 KeV BEAM

250 kV

Atomic polarization

Static magnetic field + perturbing rf field

IN THE FUTURE: REX-ISOLDE

Hardware Contributions:

Measurements of ground-state magnetic moments of short-lived Mirror Nuclei

Accelerator Layout

176 MHz RFQ

1.5 MeV/u M/q ≤ 2

1st cryostat 6 SC HWR 176 MHz 0=0.09

2nd – 6th cryostats 40 SC HWR 176

MHz 0=0.15

ECR Ion Source 20 keV/u

Phase I2006

Phase II2009

Accelerator purchasedfrom Accel GmbH,Bergisch-Gladbach,Germany

SARAF (Soreq Applied Research Accelerator Facility)

Soreq Nuclear Research CenterYavne, Israel

Accelerator Basic Characteristics

ParameterParameter ValueValue CommentComment

Ion Species Protons/Deuterons M/q ≤ 2

Energy Range 5 – 40 MeV

Current Range 0.04 – 2 mA Upgradeable to 4 mA

Operation 6000 hours/year

Reliability 90%

Maintenance Hands-On Very low beam loss

A RF Superconducting Linear Accelerator

People, group size, and activities.

Experimental groups in Israel:

Weizmann Institute of Science

Zeev Fraenkel Itzhak Tserruya

• 3 academic staff

• 1-3 post-docs

• 2-4 students

Present total staff: 8 people

• 9 PhD theses: in the period

1993-2006

The Heavy Ion Group:The Heavy Ion Group:

Group leader: Itzhak Tserruya

More information in slides 37 - 46.

Ilia Ravinovich 

Gvirol Goldring

Weizmann Institute of Science

Michael Hass 

3 scientists

4 post docs

3 students

1-2 technician -years

The WI group started its activity at ISOLDE IN 1990. The group is not a member of the ISOLDE collaboration and carried the experiments on an ad-hoc basis.

More information in slides 47 - 50.

Michael PaulEliahu Friedman

2 scientists

4 students

•5 PhD (7 M. Sc.) theses:

in the period 1990-2006

More information in slide 51.

Jechiel Lichtenstadt

Danny Ashery

Murray Moinester

Eli Piasetzky

Jonas Alster

Avivi Yavin

6 scientists

4 students

1 technician

Present active staff : 9 people

•12 Ph.D (14 M. Sc.) theses

in the period 1990-2006

More information in slides 55 - 80.

Last but not least:

The experimental program was carried in intensive collaboration with the theoreticians here in Israel:

Weizmann Institute:Weizmann Institute:

Shmuel Gurvitz  Zvi Lipkin 

Avraham Rinat

Igal Talmi 

Michael W. Kirson

Hebrew University:Hebrew University:

Barnea Nir

Avraham Gal Ami Leviatan

Victor Mandelzweig

Tel Aviv University:Tel Aviv University:

Naftali Auerbach

Leonid Frankfurt Evgeny Levin

Marek Karliner Shmuel Nussinov

Benjamin Svetitsky

The late: Judah Eisenberg

Summary and overview.

The fixed target and heavy ion program carried by Israeli groups during 1990-2005 was rich and widespread:

Energies: RHI: - GeVSNN 20017

Accelerators laboratories: CERN ,Mainz, PSI,Fermi., Brookhaven, Jefferson, TRIUMF

Physics interest: QGP, hadron structure, strong interaction, symmetry tests, nuclear structure and reaction.

Fixed target: 0-500 GeV.

d-Au

Au-Au

0 yield

Experiment Experimental group

Initiators Major equipment contribution

Major participation in analysis

Special physics topic

Management positions

PHENIX/RHIC W.I.. √ √ √ .. on executive council

CERES /CERN W.I.. √ √ √ .. Spokesperson

SELEX / Fermi T.A.U. minor √ Double charm

E991 / Fermi T.A.U. Penta,CT, LCWF

COMPASS /CERN

T.A.U. √ on executive council

E850 / BNL T.A.U. √ √ √ SRC

GeN / JLab. T.A.U. √ √

S.R.C/ JLab T.A.U. √ √ √ . Spokesperson

MAMI/Mainz T.A.U. √ √ .

Π /TRIUMF H.U. √ √ Spokesperson

MM / ISOLDE W.I.. √ √ √ Spokesperson

MOT/TRIUMF T.A.U. √

Israeli participation

The program has been carried by experimental groups in Weizmann Inst., Hebrew University , and Tel Aviv University.

Faculty - 14 The current total number of people doing research in this field (faculty, postDocs., students, technicians): ~ 30.

30 Ph.D. theses in the period 1990-2005.

Experiment Total collaboration

Number of institutes

Experimental group

Number of people

PHENIX/RHIC 300 44 (7) W.I.. 6

CERES /CERN 40 8 (5) W.I.. 6

SELEX / Fermi 100 20 (5) T.A.U. 4

E991 / Fermi 80 18 (4) T.A.U. 5

COMPASS 230 31 (7-8) T.A.U. 2

E850 / BNL 24 8 (3) T.A.U. 5

GeN / JLab. 110 20 (5) T.A.U. 5

S.R.C/ JLab T.A.U. 3

MAMI/Mainz 30 9 (3) T.A.U. 2

Π /TRIUMF 11 4 (3) H.U, 2

MM / ISOLDE 11 5 (2-3) W.I. 6

MOT/TRIUMF 22 6 (3-4) T.A.U 1

Israeli participation

Funding: I.S.F., B.S.F., G.I.F.

~400,000 €/year

FNAL-SPS-RHIC (HE: E>50GeV): ~75%

Others: ~25%

Heavy Ion Group of the Heavy Ion Group of the Weizmann InstituteWeizmann Institute

1990-1999 NA45 / CERES at CERN

1999- NOW PHENIX / RHIC at BNL

Hardware Contributions

• CERES: all gas detectors designed, constructed and

operated by the WI group:

1990-92: Readout chambers of the two RICH detectors

1995: Pad Chamber

1999: Readout chambers of the TPC

• PHENIX

1999: Design, construction and operation of Pad Chambers

2003-4: R&D of an Hadron Blind Detector for PHENIX

2005-6: Design construction and operation of HBD

CERES Spectrometer: 1992

First use of RICH detector in HI physics First use of Si radial drift chambers in an experiment Double RICH spectrometer – no real tracking Unique features to cope with the high multiplicities:

High gamma threshold tiny fraction of charged hadrons emit Cherenkov light UV detectors upstream of target not traversed by huge flux of forward particles

Field free region in RICH1 for effective recognition of 0 Dalitz and γ conversions

Radiator gasCH4 (γth = 28)

Carbon fiber mirrorCaF2 window

Si drift chambers

TMAE 2 PPAC + MWPCPad readout

CERES Spectrometer: 1995

Add tracking with a doublet of SiDC before, and a pad chamber after the double RICH spectrometer

CERES Spectrometer: 1999

Improve tracking and mass resolution with a radial TPC

Pad Chambers

Essential components of the PHENIX particle tracking

system.

Composed of three layers of pixel detectors PC1, PC2

and PC3.

PC1 (design, construction, installation…) is the

responsibility of WI group.

HBD concept ♣ windowless Cherenkov detector (L=50cm)

♣ CF4 as radiator and detector gas

♣ CsI reflective photocathode

♣ Proximity focus: detect blob not ring

♣ Triple GEM with pad readout

Very attractive features:

Unprecedented N0

Bandwidth 6 - 11.5 eV N0 ≈ 800 cm-1 ~35 pe in a 50 cm radiator

Reflective photocathode no photon feedback Pad size comparable to blob size (~10 cm2) hadrons: single pad hit, electrons: more than one pad hit

Low granularity: ~3000 pads to cover central arm acceptance

Low gain primary charge of at least 10 e/pad gain of 5 103 is enough

Final HBD design • Acceptance ||| ≤0.45 | ≤0.45 =135=135oo

• pad size a = 15.6 mm

• Number of channels 2304

• Number of detector modules 24

• GEM size 23 x 27 cm2

Management Positions

(I. Tserruya)

• 1989-91 Initiators of the CERES experiment together with the Heidelberg University group.

•1993-1998: Spokesman of CERES

• 2001-4: Member of PHENIX Executive Council

• 2004- present: Subsystem manager of the PHENIX HBD

upgrade project

Group activities 60 papers published in the refereed literature

• 21 from CERES• 39 from PHENIX• 26 of them published in PRL or PL a)

• 9 of them are top cite 100+ in SPIRES-HEP• Over 100 papers published in Conference Proceedings.

Major impact of the WI group• in the dielectron analyses of CERES• in at least 9 papers from PHENIX

49 invited talks • delivered by members of the WI Heavy-Ion Group at International Conferences or Workshops during the period 1995-2005• 12 of them on behalf of CERES or PHENIX.

a) First PHENIX paper (PRL 86, 3505 (2001)) based on an analysis of the WI group. Cited 164 times.

The Radioactive nuclear beams The Radioactive nuclear beams Group of the Weizmann InstituteGroup of the Weizmann Institute

Measurements of ground-state magnetic moments of short-lived Mirror Nuclei.

ISOLDE / CERN

Precision measurement of the 7Be(p,gamma)8B cross section.Parity non-conservation in 180mHf.( An experiment to be run in 2005).

Measurements of ground-state magnetic moments of short-lived Mirror Nuclei

23Mg (12 p + 11n )

T1/2=11.3 sec

23Na (11p + 12n)

stable

17Ne (10 p + 7n ) T1/2=109 msec

17Ne (7 p + 10n ) T1/2=4.2 sec

FUTURE: 55Ni -- 55Co, 59Zn -- 59Cu …...

8B is the major source of high-energy solar neutrinos.The discrepancies between measurements of the 8B production cross section before this work were up to 20%, reflecting the systematic problems in these measurements.

The spallation product ,7Be, produced in a PSI graphite production target were directly implanted, using the 60 keV beam at ISOLDE (CERN) on a copper substrate.

The new technique:

The measurements were done using the WI 3 MeV Van De Graaff accelerator. Measurements at a few incident proton energies (with a precision of about 2% ) allow extrapolation to zero energy –as required for the astrophysical studies.

PRL 90 (2003) 022501-1

Precision measurement of the 7Be(p,gamma)8B cross section

Parity non-conservation in 180mHf

A proposal to ISOLDE (to be run in 2005)

8+

8-

6+

0+

MeV

1.14221.0847

0.6411

0

501 KeV

The large forbidden 8- 6+ is very sensitive to even a small parity non-conserving mixing between the two proximate 8+ and 8- states.

The experiment will use the unique 180mHf beam provided by the isotope separator at ISOLDE. The continuous implantation of the 180mHf will build up low temperature nuclear oriented sample of metastable Hf nuclei that will allow measurement of the angular distribution of the gamma emission from the required transition, using Ge detectors.

The experimental nuclear physics group The experimental nuclear physics group at the Hebrew Universityat the Hebrew University

TRIUMF: Measurements of pion integral cross sections for low and the 3,3 resonance energy regions.

PSI : Precision measurement of elastic scattering of low energy π+, π- on nuclei.

Total π- p SCX cross sections between 40-240 MeV.

Phenomenological analysis of data related to pionic atoms, sigma atoms, K+ , K- and antiproton nuclear reactions.

Study of nuclear astrophysics reactions using ion beams.

AMS and other dating methods for archeological, astrophysics, environmental, geophysics, and biomedical research.

Accelerator LayoutSARAF (Soreq Applied Research Accelerator Facility)

Soreq Nuclear Research CenterYavne, Israel

Nuclear Astrophysics.

Radioactive beams.

Phase-I : Nuclear Astrophysics

1.91 MeV

proton beam

vacuum

Li jet

Graphite dump and moderator

Cu backing heat removal

target

Li jet

Neutron flux estimate :

n(Li) ~ 120 mb (Ep= 1.89 – 1.91 MeV)x(Li) ~ 0.150 mg/cm2

n/p = 1.6 x 10-6

Ip = 5 mA dn/dt = 0.5 x 1011 n/s2 x 1011 n cm-2 s-1

double-neutron capture - 135Cs yield:135Cs/133Cs ~ 10-14 /week

(Proposed by M. Paul, Hebrew University at Jerusalem)

Radioactive beams

0

20

40

60

80

100

120

0 2 4 6 8 10

Energy (MeV)

Cro

ss

se

cti

on

(m

b)

Bass 1961Savilev 1958Stelson 1957Stelson 1957

9Be(n,)6He

RIB T1/2

(ms)

reaction SARAF calculated production rate (atoms/sec)

(Before post-Acceleration)

Post accelerator count rate

(atoms/sec)

6He 807 7Li(p,2p) 1011 Dubna 1.5x105 @ 25 MeV/u

Ganil 9x107 @ 7 MeV/u

6He 807 9Be(n,) 1013

8Li 838 11B(n,) 1013 TRIUMF 8x108 @ 1.5 MeV/u

8B 770 12C(p,2p3n) 1011 Texas A&M 104 @ 8 MeV/u

Production rate at 2 mA and 40 MeV

d beam

Hot Be target Cold Be

target

9Be(d,xn)

9Be(n,)6He

fast n

2-step production

(Proposed by M. Hass, Weizmann Institute of Science)

Fixed Target Experiments at Fermilab:

E 781 (SELEX)E 665

E 791

The experimental nuclear The experimental nuclear physics group at Tel Aviv physics group at Tel Aviv UniversityUniversity

measurement of the pion valence – quark momentum distribution.

Search for particles made of 5 and 6 quarks.

Observation of Color-Transparency in Diffractive Dissociation of pions.

Double Charm Baryon Spectroscopy.

Polarization Measurement of the Lambda produced in Deep inelastic muon scattering.

COMPASS at CERN

EVA at Brookhaven National Lab.

Study of hard proton induced reactions.

Measurement of short range correlations in nuclei.E850

NA-47 (SMC) at CERN

Determination of the gluon polarization.

Spin structure of the nucleon.

Π Polarisabilities via Primakof reaction.

The experimental nuclear The experimental nuclear physics Group at Tel physics Group at Tel Aviv UniversityAviv University

Mainz Microtron MAMI

A2 collaboration

TRIUMF Radioactive beam and Neutral Magneto-Optical atom Trap

Symmetry Tests in β Decay.

Experiments at Jefferson Lab.

Measurement of the neutron charge FF: GEn

Measurement of Short range correlation in nuclei.

Hard photo-disintegration of a pp pair.

E02-013, E93-0026

E01-015 E03-101

Measurement of the π+ polarizabilities.

E 791 / FNAL : Observation of Color-Transparency in Diffractive Dissociation of pions

If there is a fully coherent interaction between the pion and all the nucleons in the nuclei and the Di-jets do not have final state interaction in the nucleus then:

)(A )( NMAM 0q A 2t

22

tdq

d 34

A

Measured :

0.1 1.5 PRL 86,4773 (2001)

In agreement with calculations: PL B304 (1993).

Danny Ashery Murray Moinester

3 scientists

E791:

4 students

E791:

2 students

1 postdoc

The COMPASS spectrometerThe COMPASS spectrometer

Spin physics program:

Gluon polarization

Transversity.

Hadron program:

Polarisabilities of pions via the Primakoff reaction.

From asymmetry measurements of lepto-produced: High pt hadron pairs.

Open charm.

How to measure ΔG/G

Photon-Gluon Fusion (PGF)

G

GAPGF

N

ggG

Two tagging methods:High pt hadron pairsOpen charm

ΔG/G from high pt hadron pair, Q2 > 1

ΔG/G = 0.06 ± 0.31stat. ± 0.06syst.

Open charm

cc

4%) (BR 0 KD

ccDD .0*

At this point only raw asymmetry is available.

Preliminary result based on 2002-2003 data.

q

q

N

Primakoff trigger

Π Polarisabilities via Primakof reaction

Hadron pilot run 2004:

30’000 – 40’000 Primakoff events on Pb after cuts.

More than four times statistics of previous experiment. Analysis in progress.

Jechiel Lichtenstadt Murray Moinester

2 scientists

Measurement of the π+ polarizabilities via

n p

Mainz Microtron MAMI electron accelerator. A2 collaboration.

1500 beam hours.

MeV 817-537 E 00' 180 - 140 cm

This experiment:

elsyststat mod5.00.35.16.11()(

Murray Moinester

1 scientist

1 student

38Ar

e+

Symmetry Tests in β Decay using the TRIUMF Radioactive beam and Neutral Magneto-Optical atom Trap (MOT).

38mK

Symmetry Tests in β Decay using the TRIUMF Radioactive beam and Neutral Magneto-Optical atom Trap (MOT).

In the standard model a 38mK(0+)38Ar(0+) β decay with back to back β-neutrino emission is forbidden (cannot be produced from a W-exchange). The atoms suspended in space decay in the MOT and the angular correlation between the recoil nuclei and the β was used to set a limit on the existence of scalar boson contribution.

See nucl-ex/0412032, PRL 94 142501 (2005).

Best direct limits on massive (a few MeV) neutrino admixtures to electron neutrino. See PRL 90 (2003) 012501.

Parity and time reversal violation tests are planned using polarized 37K decay.

Danny Ashery

1 student

Measurement of the charge neutron FF: GEn

Beam is schedule to 2006

To study nucleon pairs at close proximity and their contribution to the large momentum tail

of nucleons in nuclei.<1 fm

K 1 > KF ,

K 2 > KF

K 1

K 2

K 1 K 2

“Redefined” the problem in momentum space

A pair with “large” relative momentum between the nucleons and small CM

momentum.

NN SRC

We know that there are nucleons in nuclei with large momentum .

35%-25 K k : F12 CFor

We know that 2NN SRC are responsible for some of the large momentum components in the nucleus.

The purpose of this measurement is to find the fraction of 2N SRC in the tail of the

nucleon momentum distribution.

NN stands for pp or np pairs

KF

p

e

e’*

n

p

e

e’*

p

The method:

We measure the fraction of (e,e’p) events in which NN correlated nucleons are observed, as a function of the missing

momentum of the proton in the nucleus.

)e,e’p ( spectral function ) P ,( m

mES

)e,e’pN ( decay function

) , ,( smm PPED

),S(E d ),,( m3

mssmm PpPPED

p

e

e’

*n

p

Pm

= 3

00-6

00 M

eV/c

99 ±50

P =

300

-600

MeV

/c

Ee = 5 GeV

Ee’ = 4.15 GeV

Q2=2 (GeV/c)2

qv=1.65 GeV/c

50.40

17.80

40.80

p = 1.45 GeV/c

The selected kinematics for the measurement

X=1.245

Experimental setup

HRSHRS

p

e

e

p

Big Bite

n array

EXP 01-015

n

Scattering chamber

Milestones Jan 1998

Proposal 97-106

Hall C , n - array as a 3rd arm

Approved by PAC 13 with priority B +

Jan 2000

Parasitic 3He(e,epn) measurement in Hall A with E89 - 44

Jan 2001

P 01 -015 (update of 97-106)

Hall A, BigBite and n-array

Approved by PAC 19 with priority B+

Milestones

April 2001

Triple coincidence test d(e,epn)

Nov 2002

Measurement of low momentum, large angle positive charge singles at Hall A

Nov 2001

Parasitic measurements and shield studies

of n – detectors at Hall A

July 2003

Readiness reviewJan – April 2005

beam time

Dec 2004

Commission

Jechiel Lichtenstadt

Eli Piasetzky

2 scientists

1 student

3 technician -years