STUDY of Light -Hypernuclei by Spectroscopy of Two Body Weak

Decay Pions

Liguang TangDepartment of Physics, Hampton University

Jefferson National Laboratory (JLAB)

PR10-001 @ PAC35, January 25, 2010, JLAB

Mesonic Decay inside Nucleus

Free: p +

-

2-B: AZ A(Z + 1) +

-

Electro-production of Hypernuclei and Hyperfragments from the Continuum

e e’

* K+

p

A (A-1)

Quasi-free production (Continuum)

e e’

* K+

p

A Y(A-1)

Production of Hyperfragment (Continuum)

N

e e’

* K+

p

Aa (Aa-1)

Production of Hyperfragment (Continuum)

Ab

N

Y(Ab-1)

e e’

* K+

p

A YA

Direct production of Hypernuclei

Background

A rich source of a variety of light hypernuclei for new findings and discoveries2B decay pion is used as

the tool

Decay Pion Spectroscopy for Studyof Light -Hypernuclei

p

e’

e12C

K+

12Bg.s.

12Cg.s. -

Weak mesonic two body decay

1- 0.02- ~150 keV

Ground state doublet of 12

BB and

Direct Production

Example:

Decay Pion Spectroscopy for Light and Exotic -Hypernuclei

p

e’

e

12C

12B*

K+

4He

-

Weak mesonic two body decay (~10-10s)

Access to variety of light and exotic

hypernuclei, some of which cannot be

produced or measured precisely

by other means

4H

Fragmentation (<10-16s)

Fragmentation Process

Example:

Examples from FINUDA7Li(K-

stop, -) 7Li

7Be spectroscopy from: 7

Li 7Be + - Spin/parity: 1/2+

12C(K-stop, -) 12

C 12

C(p) 11B +

p S

P

11C spectroscopy from: 11

B 11C + -

Spin/parity: 5/2+?

High precision on ground state light hypernuclei Resolution: ~130 keV FWHM; mass precision : < ±30 keV Precise binding energy Charge symmetry breaking

Linkage between structures of hypernuclei and nuclei Determining ground state spin/parity

Search for Isomeric low lying states (Isomerism) Study the drip line limit on -hypernuclei, such

as heavy hyper-hydrogen: 6H, 7

H, and 8H

Medium modification of baryon property – B(M1) from lifetime of ground and low lying isomeric states of hypernuclei

Decay Pion Spectroscopy for StudyLight -Hypernuclei

These are rich and the most fundamental but so far

unobtainable information needed for building the correct models for

YN and Y-Nucleus interactions

Top View of the Experimental Layout

Figure 6. Schematic top view of the experimental configuration for the JLAB hypernuclear decay pion spectroscopy experiment (Hall A).

Pre-Chicaned Electron Beam

Hall C Z-axis

To Hall Dump To low power local dump

dump

Schematic Top View of New Hypernuclear

Decay Tagging System at Jlab

Hall Z-axis

To Hall Dump

K+

-

22mg/cm2

64mg/cm2

To a local photon dump

HES

94 – 140 MeV/c2.3 GeV

1.2 GeV/c

Ideal if HKS and HES move to Hall A

e

e’

Hodoscope

Lucite Č

Drift Chamber

-

K+HRS - Hadron

HRS - Electron

Septum

Trigger I: HRS(K) – Enge() - Decay Pion Experiment

Trigger II: HRS(K) – HRS(e’) - Spectroscopy Experiment

Hall A Experimental Layout

Free of Q.F. Background

Quasi-free p + - (all)

Within the HES acceptances

Three-Body Decay Background

Example: 4He 3He + p + -

P Acceptance

Hypernuclei from a 7Li Target

Breakup Mode Q value (MeV) - Decay P (MeV/c) Width (keV/c) FWHM7He - 7Li + - 114.61 165

p + 6H -23.503 (B=5.1) 6He + - 133.47 165

n + 6He -3.409 6Li + - 108.39 165

d + 5H -23.011 (B=4.1) 5He + - 133.42 ~900*

3H + 4H -16.995 4He + - 132.95 165

4H + 3H -26.981 3He + - 114.29 165

Two-Body decay – 6 possible hypernuclei

Breakup Mode Q value (MeV) - Decay P max (MeV/c) – cut offd + 5

H -23.011 (B=4.1) 4He + n + - 139.27*

2n + 5He -3.567 4He + p + - 102.42

3n + 4He -24.868 3He + p + - 103.15

Three-Body decay – Background

Hypernuclei from a 9Be Target

Breakup Mode Q value (MeV) - Decay P (MeV/c) Width (keV/c) FWHM9Li - 9Be + - 121.18 165

p + 8He -13.817 8Li + - 116.40 165

n + 8Li -3.756 8Be + - 124.12 165

2p + 7H -40.328 (B=6.1) 7He + - 135.17 ~270*

d + 7He -12.568 7Li + - 114.61 165§

2n + 7Li -12.218 7Be + - 108.02 165

3He + 6H -29.608 (B=5.1) 6He + - 133.47 165§

3H + 6He -9.745 6Li + - 108.39 165§

3n + 6Li -18.957 6Be + - 100.58 ~220**

+ 5H -11.749 (B=4.1) 5He + - 133.42 ~900*§

n + + 4H -12.005 4He + - 132.95 165§

6He + 3H -18.183 3He + - 114.29 165§

Two-Body decay – 6 additional hypernuclei

Hypernuclei from a 12C TargetBreakup Mode Q value (MeV) - Decay P (MeV/c) Width (keV/c) FWHM

12B - 12C + - 115.49 165

p + 11Be -12.280 (B=10.5) 11B + - 109.66 165

n + 11B -12.765 11C + - 105.99 165

2p + 10Li -32.908 (B=12.3) 10Be + - 119.78 165

d + 10Be -18.264 10B + - 104.31 165

2n + 10B -22.544 10C + - 95.84 165

3p + 9He -48.534 (B=7.8) 9Li + - 117.83 165

3He + 9Li -30.237 9Be + - 121.18 165§

3H + 9Be -16.072 9B + - 96.88 165*

3n + 9B -41.713 9C + - 96.71 165

4p + 8H -68.937 (B=7.1) 8He + - 137.15 165

4Li + 8He -46.961 8Li + - 116.40 165§

+ 8Li -14.444 8Be + - 124.12 165§

4H + 8Be -37.659 8B + - 97.09 165

4n + 8B -56.317 (B=6.7) 8C + - 97.21 365**

p + 4Li + 7H -73.473 (B=6.1) 7He + - 135.17 ~270*§

5Li + 7He -26.436 7Li + - 114.61 165§

5He + 7Li -25.782 7Be + - 108.02 165§

6Be + 6H -48.317 (B=5.1) 6He + - 133.47 165§

6Li + 6He -24.186 6Li + - 108.39 165§

6He + 6Li -27.663 6Be + - 100.58 ~220**§

7Be + 5H -44.499 (B=4.1) 5He + - 133.42 ~900*§

2 + 4H -22.693 4He + - 132.95 165§

9Be + 3H -27.244 3He + - 114.29 165§

Two-Body decay – 12 additional hypernuclei

(a)

2-B decay from 7He

and its continuum

(Phase I: 7Li target)

1/2+

HES PMax

HES PMin

0 2Ex Ex0 2

4H

0+

7He

1/2+

3/2+5/2+

3H

6He

1- ?

6H

5H

90.0 100.0 110.0 120.0 130.0 140.0- Momentum (MeV/c)

3B background

(b)

3B background

20Ex

10Ex 10

Ex 10Ex

2-

3/2+

5/2+

1/2+

9Li

8He

Jp=?1-

8Li

7H

1/2+

3/2+

7Li

1- ?

6Li

Additions from 9Li and its

continuum

(Phase II: 9Be target)

(c) Additions from 12B and its

continuum

(Phase III: 12C target)

12B1-

11Be11

B 10Li

10Be

5/2+ Jp=? Jp=?Jp=?10

B

Jp=?

9He

Jp=?

9Be 1/2+

9B Jp=?

8H

8Be

8B 3B background

Jp=?

Illustration of Decay Pion Spectroscopy

A

p

1 2 3 4 5 6 7 8 9 10

11

12

1

2

3

4

5

6

3H 4

H 5H 6

H 7H 8

H

6He 7

He 8He 9

He

6Li 7

Li 8Li 9

Li 10Li

11Be9

Be 10Be8

Be

11B9

B 10B8

B 12B

Light Hypernuclei to Be Investigated

Previously measuredMirror pairs

Proposal to JLAB PAC35Study of Light Hypernuclei by Pionic Decay at JLab M. Christy, C. Keppel, M. Kohl, Liguang Tang (spokesperson), L. Yuan (spokesperson), L. Zhu, Hampton University, USAN. Grigoryan, S. Knyazyan, A. Margaryan (spokesperson), L. Parlakyan, S. Zhamkochyan, H. Vardanyan, Yerevan Physics Institute, ArmeniaO. Hashimoto, S.N. Nakamura (spokesperson), Tohoku University , JapanP. Baturin, W. Boeglin, P. Markowitz, J. Reinhold (spokesperson), Florida International University, USAP. Bosted, K. de Jager, R. Ent, H. Fenker, D. Gaskell, T. Horn, M. Jones, J. LeRose (spokesperson), G. Smith, W. Vulcan, S.A. Wood, JLAB, USAE. Cisbani, F. Cusanno, S. Frullani, F. Garibaldi (spokesperson), M.L. Magliozzi, Istituto Nazionale di Fisica Nucleare, Sezione di Roma, ItalyEd.V. Hungerford, Department of Physics, University of Houston, USAL. Majling, Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Czech RepublicB. Gibson, Los Alamos National Laboratory, USAT. Motoba, Laboratory of Physics, Osaka Electro-Comm. University, JapanB. Hu, J. Shen, W. Wang, X. Zhang, Y. Zhang, Nuclear Physics Institute, Lanzhou University, ChinaD. Androic, M. Furic, T. Petkovic, T. Seva, University of Zagreb, CroatiaA. Ahmidouch, S. Danagoulian, A. Gasparian, North Carolina A&T State University, USAG. Niculescu, I. Niculescu, James Madison University, USAM. Iodice, Istituto Nazionale di Fisica Nucleare, ItalyG.M. Urciuoli, Istituto Nazionale di Fisica Nucleare, Sezione di Roma1, ItalyR. De Leo, L. Lagamba, S. Marrone, Istituto Nazionale di Fisica Nucleare, ItalyH.J.Schulze, Istituto Nazionale di Fisica Nucleare, ItalyJ. Feng, Y. Fu, J. Zhou, S. Zhou, China Institute of Atomic Energy, ChinaY. Jiang, H. Lu, X. Yan, Y. Ye, P. Zhu, University of Science & Technology of China, China.

Summary High quality and high intensity CW CEBAF

beam at JLAB made possible for high precision hypernuclear programs, among which the decay pion program is unique.

The decay pion spectroscopy program will provide precise and fundamental information needed to significantly improve our understanding on YN and Y-Nucleus interactions.

A test run in the 6GeV period is important for the development of this program for the 12GeV period.

Unlike the mass spectroscopy program, this program does not request precision and stability on beam energy.