experiment at J-PARC 2019/9/26 T. O. Yamamoto JAEA (Japan) for - PowerPoint PPT Presentation

After the previous J-PARC symposium, J-PARC E13 was successfully performed. Thank you for great support ! Recent result and future plan of hypernuclear γ -ray spectroscopic experiment at J-PARC 2019/9/26 T. O. Yamamoto JAEA (Japan) for the J-PARC E13/E63 collaboration

Contents ➢ Introduction Hypernuclear γ -ray spectroscopy at J-PARC ➢ Recent results [J-PARC E13, 2015] • 4 Λ He • 19 Λ F ➢ Future measurement [J-PARC E63] • 4 Λ H • 7 Λ Li ➢ Summary

Hypernuclear structure and spin-dependent  N interaction spin-spin spin-orbit (s  ) spin-orbit (s N ) central Tensor 1 core nuclear state Level scheme of hypernucleus Spin-dependent interaction ( spin of  =  1/2 (  in s state) ) 2 hypernuclear states Spin  0 spin-doublet Energy spacing : A - 1 10 keV ~ 1 MeV Z A Z High resolution Λ Core nucleus  -ray spectroscopy  hypernucleus (ordinal nucleus) We can get Information of spin-dependent  N interaction from level scheme

Hypernuclear structure and spin-dependent  N interaction spin-spin spin-orbit (s  ) spin-orbit (s N ) central Tensor Hypernuclear  -ray spectroscopy at KEK and BNL (1998~) 1 core nuclear state Level scheme of hypernucleus 9 11 12 15 16 Li, Be, B, C, N, O 7 Spin-dependent interaction       ( spin of  =  1/2 (  in s state) ) Strengths of spin-dependent terms were determined (for p-shell) -> Study of different (s-, sd-) shell hypernuclei at J-PARC 2 hypernuclear states Spin  0 spin-doublet Energy spacing : A - 1 10 keV ~ 1 MeV Z A Z High resolution Λ Core nucleus  -ray spectroscopy  hypernucleus (ordinal nucleus) We can get Information of spin-dependent  N interaction from level scheme

Study of radial dependence of  N spin-spin interaction ( J-PARC E13 ) Effect of spin-dependent interaction on hypernuclear level structure  (s-shell)  N(most outer shell) sd -shell p First measurement  19  F in sd-shell hypernuclei n J-PARC E13 p -shell p Well studied  7  Li in previous experiments n Charge symmetry breaking? s -shell First precise measurement Wave functions of  4  He n Nucleon and  (s-state) using Ge detector J-PARC E13 Radial dependence can be studied from these difference

Spectrometer Experimental setup (E13) for scat. particle （ SksMinus ） Use high intensity K- beam delivered from J-PARC K1.8 beam line  − − − A  A →  A +  ＊ Z Z Z ( K , )  reaction- γ coincidence experiment Tag hypernu nucl clea ear productio tion ・ Beam line spectrometer Ge detector array ・ SksMinus spectrometer Hyperball-J t  ray from hypern Detect rnuc uclei ei K － ・ Hyperball-J 4  He : liq.He terget (2.5 g/cm 2 ) Beam line p K = 1.5 GeV/c spectrometer 19  F : lip. CF 4 target (20 g/cm 2 ) p K = 1.8 GeV/c

Hyperball-J new Ge detector array Lower half of Hyperball-J Features PWO counter Large photo-peak efficiency Ge detector → ε ~6 % @1 MeV with 32 Ge detectors Target Fast readout system Low temp. Ge detector → Mechanical cooling Fast background suppressor → PWO counter For high intensity hadron beam • high count and energy deposit rate • radiation damage due to hadron beam Pulse-tube cooler

Data taking (2015) (Re-)started just after recovery from the accident at hadron facility Hyperball-J ＠ K1.8 Beam time for physics data taking 4  He : ~5 days 19  F : ~14 days Liq. Target system

Recent results Gamma-ray spectroscopy on 4 Λ He, 19 Λ F (J-PARC E13)

Result of 4 Λ He ( s -shell) Press release http://www.sci.tohoku.ac.jp/news/20151125-7613.html

Result of 4 Λ He ( s -shell) Obtained energy spectrum Level schema of mirror hypernuclei 4  H / 4  He T. O. Yamamoto et al., Phys. Rev. Lett. 115, 222501 (2015) Λ He; 1 + ) = 1.406  0.004 MeV Ex( 4 • Existence of CSB effect was confirmed ( B Λ ( g.s) and γ -ray ) • Strongly spin-dependent :  B  (1 + ) = 0.03  0.05 MeV  B  (0 + ) = 0.35  0.05 MeV

Result of 4 Λ He ( s -shell) Y. Akaishi, et. al., Level schema of mirror hypernuclei Phys. Rev. Lett. 84, 3539 (2000). 4  H / 4  He 3 body ΛΣ coupling has important roll + same spin tendency Key of CSB effect? No large effect with NSC model? Many theoretical work A. Nogga et al., Phys. Rev. Lett. 88, based on ab-initio calc. 172501 (2002). (accuracy: ~10 keV) A. Gal, Phys. Lett. B 744, 352 (2015). Need high accurate data (<10 keV) D. Gazda, A. Gal, Precise γ -ray spectroscopy NPA 954 (2016) 161 is powerful tool to study CSB We will continue with our technique in future measurement

Result of 19 Λ F ( sd -shell) Press release https://www2.kek.jp/ipns/ja/release/hyper/

Result of 19 Λ F ( sd -shell) Obtained energy spectrum 19 Λ F 19 Λ F 19 Λ F 19 Λ F S.B. Yang et al., Phys. Rev. Lett. 120, 132505 (2018) Energy of g.s. spin-doublet was determined (First data on sd-shell) Ex( 19 Λ F; 3/2 + ) +0.6 = 315.5 ± 0.4 −𝟏.𝟔 keV

Radial dependence Now, we have s-, p-, sd-shell data. Shell model calc. (Umeya & Motoba) reproduce experimental data. with NSC(e,f) model s-shell * adjusted to p-shell data Our knowledge and theoretical flamework is also good in s- and sd-shell Ave(E exp ) = 1248 keV Spin-dependent ~50% E cal = 1232 keV ΛΣ coupling ~50% 3 E cal = 692 keV J-PARC E13 p-shell (adjusted) E cal = 346 keV sd-shell J-PARC E13 T. Koike, HYP2018

Future measurement Gamma-ray spectroscopy on 4 Λ H, 7 Λ Li (J-PARC E63)

31 participants from 12 institutes J-PARC E63 (E13-2) Submitted in 2015 stage-2 approval • 4  H excitation energy (Strength of CSB effect) • 7  Li lifetime ( Λ magnetic moment in nuclear medium)

CSB effect in A=4 system Level schema of mirror hypernuclei 4  H / 4  He Need to update! Three old data We obtained are available high precision data （ J-PARC E13 ） Excitation energy [MeV] [1] [2] [3] rather large deviation [1] [2] [3] Expected

γ -ray spectroscopy of 4  H 4  H generates as hyperfragment Almost common with J-PARC E13 via the in-flight 7 Li(K - ,  - ) 7 Λ Li reaction SKS spectrometer 7 Li target Ge detector array beam line (Hyperball-J) spectrometer γ -ray stop Tagging monochromatic π − Range counter (Support hypernuclear identification) (inside Hyperball-J)

γ -ray spectroscopy of 7 Λ Li  magnetic moment in nuclear density  in nuclear medium  in free space 𝒇ℏ (𝒏 𝒕 : 𝒅𝒑𝒐𝒕𝒖𝒋𝒖𝒗𝒇𝒐𝒖 𝝂 𝜧 = 𝒓𝒗𝒃𝒔𝒍 𝒏𝒃𝒕𝒕) 𝟑𝒏 𝒕 𝒅 Mass change ? Different? Λ Li; 3/2 + → 1/2 + ] (~0.5 ps) Life time of M1 transition [ 7 →  magnetic moment 𝟐 𝝊 = 𝟐𝟕𝝆 𝟒 𝟑𝑲 𝒎𝒑𝒙 + 𝟐 Assuming weak coupling 𝟒 (𝒉 𝒅 − 𝒉 𝚳 ) 𝟑 𝑭 𝜹 between core and  𝟘 𝟗𝝆 𝟑𝑲 𝒅 + 𝟐 Key point: High stopping power shape analysis on → Dense target Doppler broaden peak Li 2 O crystal ( ρ =2.013 g/cm 3 )

Preparation status 0.9-1.1 GeV/c K - beam to adjust Doppler broadening → move to J-PARC K1.1 beam line with SKS magnet SKS: moved to K1.1 J-PARC hadron experimental facility Hyperball-J: Established K1.8 Range counter: Designing K1.8BR (will be constructed in next year) Production Li 2 O target: making crystal @JAEA target (Au) 30 GeV proton KL K1.1 High-p

Summary ➢ Gamma-ray spectroscopy is powerful tool for study of spin-dependent term and CSB in Λ N interaction ➢ Measurement for s - and sd -shell hypernuclei (E13) was successfully done. • 4 Λ He CSB in excitation energy + spin-dependence • 19 Λ F Test theoretical framework ➢ Future measurement (J-PARC E63) [stage-2 approval] • 4 Λ H Precise data for CSB study • Lifetime measurement for Λ magnetic moment in medium 7 Λ Li