Dept. of Physics, Tohoku University

H. Tamura

Hypernuclear Physics at J-PARC

Contents1. Introduction

2. S=-1

2.1 　 spectroscopy of hypernuclei

2.2 　 n-rich hypernuclei

3. S=-2

3.1 　 hypernuclear spectroscopy

3.2 　 hypernuclei

4. Experimental apparatus

5. Other plans

6. Summary

1. Introduction

N

Z

World of matter made of u, d, s quarksNu ~ Nd ~ Ns

Higherdensity

３ -dimensional nuclear chart

Strangeness in neutron stars ( > 3 - 4 0 )

Strange hadronic matter (A → ∞)

, Hypernuclei

, Hypernuclei

Str

ang

enes

s

0

-1

-2

“Stable”

Lower density

n-rich nuclei

by M. Kaneta inspired by HYP06 conference poster

Extending “Nuclear Chart” in 3D space Hyperons stabilize nuclei -> extend n/p drip lines Toward multi-strange systems -> high density nuclear matter

Baryon-Baryon interaction Unified picture of baryon-baryon interactions Understand short-range nuclear forces in terms of quarks Necessary to understand high density nuclear matter and stra

ngeness mixing in neutron stars

Impurity effects in nuclear structure Changes of size/shape, symmetry, cluster/shell structure,..

Nuclear medium effects of baryons Probed by hyperons free from Pauli effect

Motivation of Hypernuclear Physics

What we know about YN, YY interactions N Attractive (~ 2/3 of NN force) <- Z -single particle orbit data Very small LS force, small spin-spin/ tensor forces <- Z p-shell -ray data etc.

NN coupling force? <- s-shell hypernuclei p-wave force? Charge symmetry breaking (p≠n)??

NStrong isospin dependence (attractive for T=1/2,S=0) <- 4

HeStrongly repulsive in average? <- 28Si (-,K+) spectrumHow large is the repulsive (T=3/2,S=1) channel?

N Weakly attractive?? <- 12C (K-,K+) spectrum Isospin dependence???

Weakly attractive <- 6

He

-N-coupling force ???

, Unknown at all ???

Established Suggested Unknown

PRC 64 (2001) 044302

-> U = - 30 MeV (c.f. UN = -50 MeV)

J-PARC will answer

High density matter in neutron star coreLarge neutron Fermi energy -> Hyperons appear

Baryon fraction: very sensitive to YN, YY interactions

-> maximum mass, cooling speed

Hypernuclear data -> realistic calculations possible

帆座超新星残骸

かに座超新星残骸

存在

比率

密度

n star

We need N int., int., KN int. (K condensate?),

N p-wave force, NNN and YNN force,

…

2. S=-1

Present Status of Hypernuclear Spectroscopy

Updated from: O. Hashimoto and H. Tamura, Prog. Part. Nucl. Phys. 57 (2006) 564.

(2006)

2.1 S=-1

spectroscopy

of hypernuclei

Hypernuclear -ray data since 1998

(+,K+ ) at KEK-PS(K-, - ) at BNL-AGS usingGe array “Hyperball”

NaI array (13C)

“Table of Hyper-Isotopes”

PRC 77 (2008) 054315EPJ A33 (2007) 243

N spin-dependent interactions

Two-body N effective interaction Dalitz and Gal, Ann. Phys. 116 (1978) 167Millener et al., Phys. Rev. C31 (1985) 499

S SN TVp-shell: 5 radial integrals for spw.f.

∫V (r) |u(r)|2 r2dr, r = r r s pN

Well know from U = - 30 MeV

Level spacing: Linear

combination of , S, SN, T

Low-lying levels of hypernuclei

Millener’s approach

Determination of the spin-dependent force parameters

= 0.4 MeV

,S, T: consistent

S= - 0.01 MeV T = 0.03 MeV

7/2+

7Li

1/2+

3/2+

5/2+

1+

3+

6Li

9Be

2+

0+

3/2+

5/2+

1/2+ 8Be

16O

1-

0- 1/2-

3/2-1-

15OE = 1.44 + 0.05S- 0.27T

692 keV

E = 1.29 + 2.17S- 2.38T

471 keV

E = - 0.38 + 1.38S+ 7.85T

26 keV

E = -0.04 + 2.46S+ 0.99T

43 keV

-> Test and improve baryon-baryon interaction models

(meson exchange/ quark models)

S= - 0.4 MeV

E = 0.70SN

-310 keV

PRL 88 (’02) 082501PRL 86 (’00) 5963 PRL 93 (2004) 232501

PRC 73 (’06) 012501

(K-,-) reaction (pK=1.5 GeV/c) at K1.8 line using SKS + Hyperball-J (developed for higher counting rate)

　　　　

Further study of N interaction N-N coupling and three body force Charge symmetry breaking (n≠p?) Radial dependence (Interaction range)

　　　 4He, 10

B, 11B, 19

F

g in a nucleus from spin-flip B(M1) 7

Li

r (s-dN) > r (s-pN)

sensitive to interaction rangeand exchanging meson mass

(K-,- )

??

Very large CSB !?Not theoretically understood.

B(MeV)

E13 (Tamura et al.)-ray spectroscopy of light hypernuclei

g factor of in nucleus

Direct measurement extremely difficult

(~ 0.1-- 0.2 ns)

B(M1) of -spin-flip M1 transition -> g

applied to “hypernuclear shrinkage” in 7

Li from B(E2) : PRL 86 (’01)1982

Doppler Shift Attenuation Method :~100%

in nucleus -> medium effect of baryons

core nucleus

Jc

Jc +1/2

Jc -1/2

M1

in s-orbit

"hypernuclear fine structure"

g

hypernucleus

ψ↑ψc

ψ↓ψcin s-orbit

gc

reduction of mass-> enhancement of ??

-> Precise B(M1) measurement (~5%) of 7Li at J-PARC

mq : Const.

quark mass

eh2mqcq=

2.2 S=-1

n-rich hypernuclei

Search for n-rich hypernucleiby (Stopped K-, +)

Only upper limitBackground from Sigma decay

9He

12Be

16C

6H

7H

Neutron-rich hypernucleus

First data on n-rich hypernucleus

10B (-, K+) 10Li

Almost no background

Saha et al., PRL 94 (2005) 052502

11.1±1.9 nb/sr

(KEK E521, K6+SKS)

- p p -> n K+

p~1.2 GeV/c

Physics Interest

coherent coupling -> more bound?

Behavior of n-halo with a

Production mechanism? 2-step charge exch. -p->0n, 0p->K+etc.) - admixture - p->- K+, - p->n)

coherent coupling

Akaishi et al., PRL 84 (2000) 3539

E10 (Sakaguchi et al.)Study on Neutron-Rich Hypernuclei

Produce neutron-rich hypernuclei by the double charge-exchange (DCX) reaction

ordinary nucleiordinary nuclei

this studythis study

pn

unbound “Hyperheavy hydrogen”: deeply bound

6H5H

NCX: (KNCX: (K,,), (), (++,K,K++) reaction) reaction

SCX: (e,e’KSCX: (e,e’K++), (K), (K,,), (), (,K,K00) reaction) reaction

DCX: (KDCX: (K,,),), (,K+) reactionreaction

DCXDCX

SCXSCX

NCXNCX

-hypernuclei-hypernuclei

n

n

n

pnn n

n

Akaishi:Glue-like role of

(B=4.4 MeV)

NN coherentcoupling ( +1.4 MeV)

3.1 S= -2

-hypernuclei

First spectroscopic study of

S=-2 systems in (K-,K+) reaction First step to multi-strangeness

baryon systems

N Interaction Attractive or repulsive? How large?

<- -nuclear potential depth Isospin dependence ?

<- Different targets N-coupling force? <- p→ conversion width

<- andhypernuclear mixing states

-> Take a similar spectrum for (K-,K+) reaction

E05 (Nagae et al.)-hypernuclear spectroscopy by (K-,K+)1

st priorit

y K- p -> - K+

Previous data

on N interaction

(BNL AGS E855)PK=1.8 GeV/cM=9.9 MeV/c2 (FWHM) for p(K−,K+)−

−20 < E < 0 MeV 89±14 nb/sr θ< 8° 42± 5 nb/sr θ<14° V = -14 MeV?

V= -20MeV

V= -14MeV

[counts

/0.5

MeV

]

-B [MeV]

s

p

Emeas. = 3 MeVFWHM

Expected 12C (K-,K+) 12Be Spectrum

Precision:

Peak Position: 0.1 - 0.3 MeV

Width: 0.2 - 1 MeV

3.2 S=-2

hypernuclei (and - atoms)

A golden event of Hypernuclei

Takahashi et al., PRL 87 (2001) 212502

The first well-identified double hypernucleus event

B =1.01±0.20 +0.18 MeV- 0.11

Interaction between is weekly attractive.

Nagara event

n

p

KEK E377 Emulsion-counter hybrid method

~103 stopped -

produced from K- p -> - K+ reaction

“Triple magic nucleus”p(0s)2 n(0s)2(0s)2

Mass ->

PRL 87 (2001) 212502

Ten times more events of hypernuclei

>104 stopped -, ~102 hypernuclei Details of interaction strength correlation (H dibaryon-like state) in nucleus from “”-> p decay

Measure - -atomic X-rays with Hyperball-J Shift and width of X-rays -> -nuclear potential Stopped - events identified from emulsion

Measure tracks by counters

E07 (Nakazawa, Imai, Tamura et al.) 　S=-2 Systems with Emulsion-Counter Hybrid Method

“”-> p decay event

E03 (Tanida et al.)　 - atomic X rays by (K-,K+)- on Fe target

4. Experimental Apparatus

K1.8

Handron Hall

Beam Dump

K1.8 (Fall,2009~)

K1.8BR (Dec.2008~)

K1.1 (when?)

KL

K0.8 (when?)

30 (→ 50) GeV primary beam

Productiontarget (T1)

Hadron Hall

SKS

hypernuclei

hypernuclei-atomic X rays spectroscopy

n-rich hypernuclei search nucleus

K- nucleus bound statesK- atomic X rays, nucleus

spectroscopy hypernucleiYN scattering nucleus

1.5 GeV/c

An Example of Setup

(E13)

-

K-

1.4 GeV/c

Hyperball-J

SKS superconducting magnet 　

K1.8 beamline spectrometer

SKS spectrometer(SksMin

us)

SKS spectrometerModified SKS magnet

Disassembled Jan.15-30 Under modification of cooling system Assemble at J-PARC site (2008 Sep.-Oct.)

SksPlus for (K-,K+)

Additional magnet produced

using an old iron yoke

1.4 GeV/c

Setup of E07

# Beam : K- (1.7GeV/c), 　　　 3 x 105 K-/spill with K-/- > 6 at K1.8 beam-line (~20% of 9A)

# Trigger : (K-, K+) => 104 - stopping events (more than 10 times higher statistics than E373)

Almost sameas PS-E373

Double-sided Si Strip Detector

Faster emulsion scanning system

Hyperball-J

KURAMA spectrometer(existing)

5. Other plans

High resolution (~0.2 MeV) (±,K) spectroscopy for (n-rich) , hypernuclei (Noumi)

Weak decay of hypernuclei (Bhang)

spectroscopy of heavy hypernuclei and n-rich hypernuclei (Tamura)

Light hypernuclear systems (Tamura)

N, N, N) scattering experiments (Ieiri, Miwa)

6. Summary

Hypernuclear physics is one of the most important physics subjects at the J-PARC Hadron Hall.

spectroscopy of hypernuclei using Hyperball-J will further investigate N interactions. Nuclear medium effect can be also studied from in-medium g.

n-rich hypernuclei to be studied at J-PARC will extend the hypernuclear chart and clarify the N-N mixing.

hypernuclear data will provide the strength of N interaction for the first time.

Manyhypernuclear samples will be found, establishing the interaction, and revealing a possible correlation.