Spectroscopy of hypernuclei. Spectroscopy of hypernuclei. Alessandro Feliciello I.N.F.N. - Sezione di Torino

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1 Spectroscopy of hypernuclei Spectroscopy of hypernuclei Alessandro Feliciello I.N.F.N. - Sezione di Torino

2 2 Outline Discovery potential of the strangeness nuclear physics recent experimental results unexpected effects Need of sub-mev resolution apparatuses γ-ray spectroscopy Proposal for new experiments

3 Physics output (S=-1) 3 nuclear nuclear models models spectroscopy spectroscopy low-energy low-energy N-Y N-Y interaction interaction neutron neutron rich rich -hypernuclei -hypernuclei n p p n n p p n p p n medium medium effect effect 4B 4B weak weak interaction interaction (weak) (weak) decay decay quark quark substructures substructures

4 Open questions 4 (low-energy) YN interaction detailed knowledge of the hypernuclear fine structure evaluation of the spin dependent terms of the N interaction measurement of angular distribution of γ rays determination of spin and parity of each observed level

5 Spin-dependent forces 5 V The The simple simple structure of of light light hypernuclear system system can can be be described in in the the frame frame of of the the shell shell model model V V V r σ N ( r) = ( r) + N 0 σ r r s N s r )( σ V r σ T Each Eachof of the the 4 terms terms (, (, S,, S N, N, T) T) correspond to to a radial radial integral that that can can be be phenomelogically determined from from the the low-lying level level structure of of p-shell p-shell hypernuclei The The knowledge of of these these characteristics of of the the N N interaction allows allows to to improve baryon-baryon interaction description r l r ( r) + ( r) N ( r)[3( r r σ )] + T N S S N r s + V N ( r) r l N r s N

6 Where do we stand? 6 HYPERBALL KEK E419: (π (π + +,K,K + ) + 7 ) 7 Li Li BNL E930: (K (K -,π -,π -- ) 7 ) 7 Li Li KEK E509: (K (K -,π -,π -- ) 7 ) 7 Li Li = 0.43 S =-0.01 S N =-0.40 N T = 0.03 D.J. D.J. Millener, Millener, Nucl. Nucl. Phys. Phys. A A (2005) (2005) 48c 48c

7 Charge symmetry breaking 7 p n n 4 H p n n 4 He I = 0 q = 0 p n p p n if the charge symmetry holds exactly Possible explanations: Σ 0 mixing N ΣN coupling p p = n 4 4 B ( H) B ( He ) p p more attractive than n n A.R. A.R. Bodmer Bodmer et et al., al., Phys. Phys. Rev. Rev. C C (4) (4) (1985) (1985)

8 Open questions 8 (low-energy) YN interaction detailed knowledge of the hypernuclear fine structure evaluation of the spin dependent terms of the N interaction measurement of angular distribution of γ rays determination of spin and parity of each observed level Impurity nuclear physics measurement of transition probability B(E2) information on the size and deformation of hypernuclei measurement of nucleus core shrinking glue-like role of

9 Impurity nuclear physics 9 A hypernucleus can be be considered the outcome of of a genetic engineering manipulation applied to to the nuclear physics domain The introduction of of 1 (or 2) 2) hyperons in in a nucleus may give rise to to various changes of of the nuclear structure changes of the size and of the shape changes of the cluster structure manifestation of new symmetries change of collective motions study of of hypernucleus level schemes and B(E2) Doppler-shift attenuation method

10 The glue-like role 10 KEK KEK E419 E419 7 Li 7 B( E2; Li : 5 / 2 6 B( E2; Li : E2(5/2 + 1/2 + ) τ = 5.8 ps K. K. Tanida Tanida et et al., al., Phis. Phis. Rev. Rev. Lett. Lett (10) (10) (2001) (2001) / ) + +. ) 3. 6 ± = ± 0. 9 B(E2) r 4 shrinkage of of 66 Li Licore by by ~ 20% e fm 2 4 e fm 4 1 3

11 Open questions 11 (low-energy) YN interaction detailed knowledge of the hypernuclear fine structure evaluation of the spin dependent terms of the N interaction measurement of angular distribution of γ rays determination of spin and parity of each observed level Impurity nuclear physics measurement of transition probability B(E2) information on the size and deformation of hypernuclei measurement of nucleus core shrinking glue role of Properties of hyperons in nuclear matter (medium effect) measurement of transition probability B(M1) g-factor value for in nuclear matter

12 Medium effect 12 If If the the mass or or the the size size of of a hyperon is is modified in in a nucleus, its its magnetic moment may may be be changed B 2 z z z ( M1) φlo μ φup = φlo g N J N + gj φup ( g N g 2 ) B(M1) can can be be derived from excited states lifetimes Doppler-shift attenuation method γ-weak coincidence method 2

13 Physics output (S=-2) 13 nuclear nuclear models models spectroscopy spectroscopy low-energy low-energy Y-Y Y-Y interaction interaction strangelets strangelets p n n p astrophysics astrophysics H dibaryon dibaryon existence existence (weak) (weak) decay decay S=-2 S=-2 system system g.s. g.s. H particle particle mass mass

14 Observed -hypernuclei : Danysz et al. 1966: Prowse 10 Be 6 He 13 B (emulsion) (emulsion, Dalitz criticises the interpretation) 1991: KEK-E176 (or, emulsion counter hybrid experiment) 2001: BNL-E : KEK-E : KEK-E373 4 H 6 He 10 Be 10 Be Ξ + 6 C He+ He + t He 5 He + p + π

15 DAΦNE 15 energy 510 MeV luminosity cm -2 s -1 σ x (rms) 2.11 mm σ y (rms) mm σ z (rms) 35 mm bunch length 30 mm crossing angle 12.5 mrad frequency (max) MHz bunch/ring up to 120 part./bunch current/ring 5.2 A (max) A Z e Κ + e stop + + φ Κ A A Z ( Z Z A Z Κ + + π ( Z + 1) + π ( A 2) ( A 2) + n + n 1) + p + n

16 16 Is the integration possible? Is the integration possible? Hyperball FINUDA

17 17 Experimental challenges Experimental challenges JRA6 Do HPGe crystals work in (strong) magnetic field? GSI To what extent the energy resolution is affected? How to minimize the mechanical interferences? GSI

18 18 FINUDA2 X COOLER II, AMETEK, ORTEC Geometrical acceptance reduced to to 82% 82%

19 19? Interested community Interested community HyperGamma JRA6

20 Strategy 20 Total synergy with the I3HP JRA6 project study of HPGe crystal performance in strong magnetic field Close collaboration with TORTOLISO experiment, approved by INFN CSN 5 Cagliari-Torino Collaboration production of LYSO crystals by an Italian firm Contacts with INFN Groups, with solid experience on HPGe exploitation of previous INFN investment PRIN dedicated to an operative test of final HPGe configuration in magnetic field last step before to go

21 21

22 PANDA Collaboration PANDA Collaboration 22

23 Strategy 23 possible Joint Research Project in the Seventh Framework Programme (FP7) further study of HPGe crystal performance with the electromechanical cooling system design of a 3-crystal cluster, equipped with new readout electronics strict collaboration with INFN Groups, with solid experience on HPGe exploitation of previous INFN investment PRIN dedicated to an operative test of chosen HPGe configuration in magnetic field last step before to go

24 Summary 24 strangeness nuclear physics still has a great discovery potential spectroscopy of hypernuclei offers a couple of interesting opportunity to successfully employ the existing HPGe detectors: FINUDA at DAΦNE (LNF/INFN) PANDA at HESR (FAIR/GSI) A. Bracco, F. Camera and S. Lenzi valuable support is warmly acknowledged