Be, via the 12 C( K - , K + ) reaction at 1.8 GeV/ c S. Kanatsuki - - PowerPoint PPT Presentation

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Be, via the 12 C( K - , K + ) reaction at 1.8 GeV/ c S. Kanatsuki - - PowerPoint PPT Presentation

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Observation of hypernucleus, 12 Be, via the 12 C( K - , K + ) reaction at 1.8 GeV/ c S. Kanatsuki for the J-PARC E05 Collaboration NSMAT2016 2016/11/21 2016/11/21 Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki 1

slide-1
SLIDE 1

Observation of Ξ hypernucleus, 12

ΞBe,

via the 12C(K-,K+) reaction at 1.8 GeV/c

  • S. Kanatsuki for the J-PARC E05 Collaboration

NSMAT2016 2016/11/21

2016/11/21 Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki 1

slide-2
SLIDE 2
  • Introduction

– BNL-E885 and KISO event

  • J-PARC E05 experiment

– plan – pilot run in 2015

  • analysis status
  • discussion
  • Summary

2016/11/21 Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki 1

Observation of Ξ hypernucleus, 12

ΞBe,

via the 12C(K-,K+) reaction at 1.8 GeV/c

slide-3
SLIDE 3

Introduction

2016/11/21 Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki 2

slide-4
SLIDE 4

BNL-E885

  • 12C(K-, K+)12

ΞBe at 1.8 GeV/c

  • dσ/dΩ ( -20 < E < 0 MeV)

– θ<14°: 67 events, 42±5 nb/sr – θ<8°: 42 events, 89±14 nb/sr

  • mass resolution 14 MeV (FWHM)

‒ no clear peak ‒ shape analysis à VΞ ～ -14 MeV ?

2016/11/21

Bound region

  • P. Khaustov et al., PRC 61 (2000) 054603

Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki

(suggestion) ü evidence of existence of Ξ- bound state ü VΞ ～ -14 MeV (BΞ = ～4.5 MeV) ? ü VΞ = -20 MeV is less favored

3

slide-5
SLIDE 5

“KISO” event

  • Ξ-14N system found in KEK-E373

– Ξー + 14N → 10ΛBe+5ΛHe – BΞ = 1.03±0.18 or 3.87±0.21 MeV ±Γ/2

2016/11/21

  • K. Nakazawa et al., PTEP (2015) 3, 033D02

Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki

ü deeply bound state ü Ξ hypernuclei do exist ü stimulates systematic study

reported in the 22th J-PARC PAC

4

slide-6
SLIDE 6

J-PARC E05

2016/11/21 Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki 5

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SLIDE 7

J-PARC E05 Collaboration

  • Kyoto University

–

  • H. Ekawa, S. Kanatsuki, T. Nagae, T. Nanamura, M. Naruki
  • JAEA

–

  • S. Hasegawa, K. Hosomi, Y. Ichikawa, K. Imai, H. Sako, S. Sato, H. Sugimura, K. Tanida
  • Osaka University

–

  • K. Kobayashi, S.H. Hayakawa, T. Hayakawa, R. Honda, Y. Nakada, M. Nakagawa, A. Sakaguchi
  • Tohoku University

–

  • Y. Akazawa, M. Fujita, K. Miwa, Y. Sasaki, H. Tamura
  • KEK

–

  • K. Aoki, T. Takahashi, M. Ukai, T. O. Yamamoto
  • Korea University

– J.K, Ahn, W. Jung, S. H. Kim

  • Torino University

–

  • E. Botta, A. Feliciello, S. Marcello
  • JINR

–

  • P. Evtoukhovitch, Z. Tsamalaidze,
  • Osaka University, RCNP

–

  • T. Gogami, K. Shirotori
  • Seoul National University

– J.Y Lee, T. Moon

  • Gifu University

–

  • S. Kinbara
  • Kitasato University

–

  • T. Hasegawa

2016/11/21 Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki

2015/11/19 J-PARC K1.8 counting room

6

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SLIDE 8

J-PARC E05 experiment

Missing-mass spectroscopy of Ξ- hypernucleus via the 12C(K-,K+)12

ΞBe

  • bserve peaks of the bound state
  • much improved mass resolution: ＜2 MeV
  • deduce the information of ΞN potential

High-resolution measurement

  • with new K+ spectrometer, “S-2S”
  • developed for KK reaction spectroscopy
  • magnet construction completed in 2015
  • to be installed in 2018??

2016/11/21 Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki

3 m Q13 Q12 D4 BH2 BAC BC4 BC3 Q11 Q10 MS2 Q9 BFT BH1 SDC1 Target

Q1 Q2 D1 Tracker1,2 Target Tracker3,4 TOF AC WC 1 m

  • Scat. K+

~1.4 GeV/c

D1 Q2 Q1 SDC1,2 WC AC TOF SDC3,4

Beam K− 1.8 GeV/c Target

[Beam spectrometer] dp/p<1×10-3 already working at K1.8BL

[S-2S spectrometer] dp/p～6×10-4 dΩ 60 msr High-resolution run with S-2S

7

slide-9
SLIDE 9

3 m Q13 Q12 D4 BH2 BAC BC4 BC3 Q11 Q10 MS2 Q9 BFT BH1 SDC1 Target

J-PARC E05 experiment

Missing-mass spectroscopy of Ξ- hypernucleus via the 12C(K-,K+)12

ΞBe

  • bserve peaks of the bound state
  • much improved mass resolution: ＜2 MeV
  • deduce the information of ΞN potential

High-resolution measurement

  • with new K+ spectrometer, “S-2S”
  • developed for KK reaction spectroscopy
  • magnet construction completed in 2015
  • to be installed in 2018??

Pilot measurement: 2015 autumn

  • beam: 6×105 K-/spill, K/π ~0.8 (39kW)
  • by using the SKS spectrometer
  • purpose

– optimization of beam momentum – hypernuclear spectrum with medium resolution in wide range

2016/11/21 Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki

3 m Q13 Q12 D4 BH2 BAC BC4 BC3 Q11 Q10 BFT BH1 SKS SDC1 SDC2 SDC3 SDC4 TOF AC LC Target

  • Scat. K+

~1.4 GeV/c Beam K− 1.8 GeV/c Target: CH2 9.54g/cm2 Carbon 9.36g/cm2

[Beam spectrometer] dp/p<1×10-3 already working at K1.8BL

[SKS spectrometer] dp/p～3×10-3 dΩ 110 msr Pilot run in 2015 Oct. 26 ‒ Nov. 19

7 [S-2S spectrometer] dp/p～6×10-4 dΩ 60 msr

slide-10
SLIDE 10

Analysis

2016/11/21 Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki 8

slide-11
SLIDE 11

]

2

Mass sqr. [GeV

  • 0.2

0.2 0.4 0.6 0.8 1 1.2 1 10

2

10

3

10

Mass square SKS

w/ dY cut

Mass square SKS

3 m Q13 Q12 D4 BH2 BAC BC4 BC3 Q11 Q10 BFT BH1 SKS SDC1 SDC2 SDC3 SDC4 TOF AC LC Target

(K-, K+) selection

2016/11/21

Kー beam

  • Scat. K+

Kー

πー

p π＋

Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki

K＋

Beam TOF

Beam Spectrometer SKS

9

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SLIDE 12

Missing Mass (GeV)

1.3 1.3051.311.3151.321.3251.331.3351.341.3451.35

Counts /0.5 MeV

100 200 300 400 500

) at 1.8 GeV/c

+

, K

  • Missing mass p(K

) at 1.8 GeV/c

+

, K

  • Missing mass p(K

Ξ- production

2016/11/21

  • Missing mass

Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki 10

ü detectors and analysis working well ü energy calibration ü ΔM ~5.4 MeV

(GeV/c)

lab

  • K

p

1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3

b/sr) µ (

°

<18

  • >
  • /d
  • <d
  • 10

20 30 40 50 60

Present data J.P.Berge et al. (1966) G.Burgen et al. (1968) P.M.Dauber et al. (1969) Eyeball fit (C.B.Dover et al.)

θlab＜18°

Present data are normalized arbitrarily to fit the past data.

slide-13
SLIDE 13
  • B.E. (MeV)

50

  • 50

100 150 200 250 300 350 400

(Counts /2 MeV)

100 200 300 400 500 600 700

) (Carbon)

+

, K

  • C(K

12

Binding energy ) (Carbon)

+

, K

  • C(K

12

Binding energy

Energy spectrum

2016/11/21 Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki

ΔM ～6 MeVFWHM (estimated) QF-Ξ : 60k events θ < 30 deg

Bound region

11

B.E. = M(11B) + M(Ξ−) − M(12

ΞBe)

slide-14
SLIDE 14

B.E. = M(11B) + M(Ξ−) − M(12

ΞBe)

  • B.E. (MeV)

50

  • 50

100 150 200 250 300 350 400

(Counts /2 MeV)

100 200 300 400 500 600 700

) (Carbon)

+

, K

  • C(K

12

Binding energy ) (Carbon)

+

, K

  • C(K

12

Binding energy

Energy spectrum

2016/11/21 Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki

ΔM ～7 MeVFWHM (estimated) QF-Ξ : 60k events θ < 30 deg

Bound region

11

  • B.E. (MeV)

80

  • 60
  • 40
  • 20
  • 20

40

(Counts /2 MeV)

20 40 60 80 100 120 140 160 180 200 220

) (Carbon)

+

, K

  • C(K

12

Binding energy ) (Carbon)

+

, K

  • C(K

12

Binding energy Bound region

slide-15
SLIDE 15
  • B.E. [MeV]

180

  • 160
  • 140
  • 120
  • 100
  • 80
  • 60
  • 40
  • 20
  • 20

Counts /2 MeV

2 4 6 8 10 12 14 16 18 20 22 ) (Carbon + CH2)

+

, K

  • C(K

12

Binding energy

Background level : 1.08 Counts /2 MeV #Event (20>B.E.> 0 MeV) : 55 Counts

) (Carbon + CH2)

+

, K

  • C(K

12

Binding energy

Background

2016/11/21 Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki

Background level 1.1 Counts/bin (average in -180 ～ -80 [MeV])

12

12 ΛΛBe

slide-16
SLIDE 16
  • B.E. [MeV]

80

  • 70
  • 60
  • 50
  • 40
  • 30
  • 20
  • 10
  • 10 20

Counts /2 MeV

2 4 6 8 10 12 14 16 18 20 22

) (Carbon + CH2)

+

, K

  • C(K

12

Binding energy ) (Carbon + CH2)

+

, K

  • C(K

12

Binding energy

Energy spectrum

2016/11/21 Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki

Bound region

Background level 1.1 Counts/bin (average in -180 ～ -80 [MeV]) ü significant excess in 20＞-E＞0 MeV, 39 events

13

slide-17
SLIDE 17

Comparison with BNL-E885

2016/11/21 Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki

ü spectrum shapes are consistent

  • B.E. [MeV]
  • 80
  • 70
  • 60
  • 50
  • 40
  • 30
  • 20
  • 10

10 20

Counts [/2 MeV]

5 10 15 20 25 30 35

Comparizon of BNL and J-PARC

BNL E885 (x0.58) J-PARC E05

Comparizon of BNL and J-PARC

14

(θ＜14° )

slide-18
SLIDE 18

Summary

2016/11/21

  • Ξ-hypernucleus

– exists, but binding energy is not determined yet – baryon-baryon interaction and strange nuclear matter

  • J-PARC E05 pilot measurement

– first experiment on S=-2 physics at J-PARC – analysis status

  • significant excess in the bound region
  • suggestion

– two bound states – deeper potential depth >14 MeV (suggested in BNL-E885) – prospect

  • cross section estimation
  • angular distribution of elementary/QF process

Neutron Star Matter (NSMAT2016) Tohoku Univ. / S. Kanatsuki 15