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.