Nuclear Physics Work Group Meeting Report (6/17/05)

● Nine presentations over 4.5 hours.

● Targets

– Deuteron: 3 (Gilfoyle, Egiyan, Asryan).

– 4He: 1 (Strauch).

– 3He: 3 (Ilieva, Ireland (2)).

– A>4: 2 (Wood, Egiyan, Manly).

● Beams

– Electron: 7 (Ireland(2), Manly, Gilfoyle, Egiyan, Asryan, Wood)

– Photon: 2 (Strauch, Ilieva)

A Very Preliminary Analysis of the Two-Deuteron Photodisintegration of 4He

Steffen Strauch

● 4He(,dd) reaction identified for E = 350-1200 MeV

● Differential cross section.

– CLAS: minimum at cm

=90o where E2 transition dominates.

– Differs from SAL, Bonn at 300 MeV.

● Total Cross Section

– tot

= 40-400 pb.

– Agrees with Bonn data at lowest energy

Two-body Breakup of 3He with Real PhotonsYordanka Ilieva

● 3He -> pd is complimentary to He -> ppn with respect to studying three-body mechanisms.

● CLAS data at photon energies 0.4-1.5 GeV and proton CM angles 40º -140º .

● The invariant cross sections fall off extremely fast with s: power of s ~ -22.

● The differential cross sections exhibit large forward-backward asymmetry: one order of magnitude.

● The slope of the dfferential cross sections is independent of Eg.

● The cross sections are sensitive to three-body mechanism contributions.

● A comparison with J.M. Laget's model shows that the relative contribution of the three-body mechanisms is larger at 600-800 MeV than at higher photon energies. This has been also observed in the three-body breakup of 3He.

Electroproduction of s in 3He

● Modification of s in nuclear medium?● Electroproduction of 0 -p● Electroproduction of + 0p● Comparison with + 0p from free proton

(CLAS ANALYSIS 2001-008, +papers)

Joe Donnelly

Dave Ireland

University of Glasgow

Partial Wave Coefficientsp(e,e’0p)

3He(e,e’-p)

Extracted Multipole Distributions3He(e,e’-p)

Three-body forces studied in 3He(e,e’pp) reactions

Dan Watts

(University of Edinburgh)

Dan Protopopescu

Dave Ireland

(University of Glasgow)

Spectator or Active Neutron?

pm < 0.2 GeV/c (spectator)

pm > 0.2 GeV/c (active)

Variation with

00 < < 300

300 < < 600

600 < < 900

900 < < 1200

1200 < < 1500

1500 < < 1800

All

= 50, 150, 250, 350, 450 MeV

Experimental Data

CLAS data and neutrinos – summary S. Manly, Univ. of Rochester

Neutrinos have mass and oscillate; compelling us to perform Neutrinos have mass and oscillate; compelling us to perform high statistics experiments in the one-few GeV range with high statistics experiments in the one-few GeV range with reduced systematic errors. reduced systematic errors.

1)1) High statistics, fully active, highly segmented neutrino expt. High statistics, fully active, highly segmented neutrino expt. (MINER(MINERA) approved at FNAL. A) approved at FNAL.

2)2) Should produce Should produce A scattering.A scattering.

3)3) data complementary to JLab eA data. data complementary to JLab eA data.

See MINERSee MINERA proposal – hep-ex/405002A proposal – hep-ex/405002

1)1) New set of long baseline, expensive, neutrino expts to measure last New set of long baseline, expensive, neutrino expts to measure last angle of neutrino mass mixing matrix and possibly look for CP angle of neutrino mass mixing matrix and possibly look for CP violation in the neutrino sector (MINOS, T2K, NOviolation in the neutrino sector (MINOS, T2K, NOA) are being A) are being designed/built (MINOS already taking data. These experiments designed/built (MINOS already taking data. These experiments can benefit greatly from MC constraints from eA data. can benefit greatly from MC constraints from eA data.

JUPITER - Jlab Unified Program to Investigate nuclear JUPITER - Jlab Unified Program to Investigate nuclear Targets and Electroproduction of ResonancesTargets and Electroproduction of Resonances

Study eA processes in the one-few GeV region that are complementary Study eA processes in the one-few GeV region that are complementary to and useful for understanding neutrino scattering in the same energy to and useful for understanding neutrino scattering in the same energy range.range.

With the push in neutrinos, complementary expts (to eA) can be done that will With the push in neutrinos, complementary expts (to eA) can be done that will help us understand the nucleon, resonance production, nuclear effects, etc.help us understand the nucleon, resonance production, nuclear effects, etc.

Also use this information to reduce systematic errors in the neutrino experiments, Also use this information to reduce systematic errors in the neutrino experiments, thus contributing to the fundamental exploration of the neutrino sector.thus contributing to the fundamental exploration of the neutrino sector.

JLab Hall C – E04-001 and E02-109 – Separated vector JLab Hall C – E04-001 and E02-109 – Separated vector structure functions for different nuclear targetsstructure functions for different nuclear targets

Neutrinos - MINERNeutrinos - MINERA, also feed info to other expts.A, also feed info to other expts.

Phenomenology – development of structure function Phenomenology – development of structure function parametrizations through resonance region (using duality)parametrizations through resonance region (using duality)

PeoplePeople

R. Bradford at Rochester (0.5 CLAS, 0.5 MINERR. Bradford at Rochester (0.5 CLAS, 0.5 MINERA)A)

Summer student working on CLAS analysis (David Sher)Summer student working on CLAS analysis (David Sher)

J. Steinman working on Hall C E04-001J. Steinman working on Hall C E04-001

Summary of Progress Report for Analysis of d(e,e’p)n for the E5 Run Period

Jerry Gilfoyle, Robert Burrell, and Kristen GreenholtFor E=2.6 GeV, normal torus polarity, the fifth structure function asymmetry A’LT is sensitive to the electron fiducial cuts. This appears to reflect the underlying Q2 distribution in the data. Other tests show no problems with the event reconstruction near the coils.

We have generated fiducial cuts for the proton for d(e,e’p)n using a mixed sample of protons and positive pions. The proton fiducial cuts have little effect on A’LT.

Study of Short Range Correlations in A(e,e’) Reaction at 1 <xB<3

K. Egiyan, N. Dashyan, M. Sargsian, M. Strikman, L. Weinstein

● Will use published CLAS and Brookhaven data to study isotopic composition of 2-nucleon SRC in 12C.

● Using the data from C(p,2p+n) measurements of EVA experiment at BNL for isotopic estimates.

● Collaborating with authors E.Piasetzky and J.Watson of the BNL experiment.

● Preparing a paper for Science.

d(e,e'p)n exclusive reaction analysis: extraction of cross section

G.Asryan, K.Egiyan● Fitted the missing mass spectra to

extract the neutron yield and calculate the measured cross section.

● Consistent within ~15% with previous cross sections where neutron yields were determined from simple cuts on missing mass spectra.

Status of g7 experiment on search for medium modifications of vector mesons.

Absorption of and mesons observed as target A increases. For 208Pb, these VM almost disappear completely.

Plan is to extract N and N cross sections from experimental normalized yields and realistic model of final state interactions.

Exp data – NA50 collaboration, M. Gonin et al., NPA 610 (1996) 404c

Theory – W. Cassing and E. L. Bratkovskaya, NPA 623 (1997) 570

Suppression of J/

Absorption of Vector Mesons in Nuclei – N and N Cross SectionsMichael Wood, UMass