1. The Physics Case 2. Present Status 3. Hypersystems in pp Interactions 4. The Experiment Future Experiments on Hypernuclei and Hyperatoms _

1. The Physics Case

baryons tagged with a strange quark as a probe of the nuclear structure nuclei as a femto-laboratory for strange baryons Two Sides of a Coin mesonic decay of hypernuclei mesonic decay of hypernuclei w  N  suppressed by Pauli blocking p F 270MeV/c w  N  p N 100MeV/c free  decay non-mesonic decay of hypernuclei non-mesonic decay of hypernuclei w  N  s N N To use nuclei as a QCD-laboratory we have to understand the laboratory

s=1: -, -hypernuclei nuclear structure, new symmetries the presence of a hyperon may modify the size, shape... of nuclei new specific symmetries Y-N interaction strange baryons in nuclei weak decay s=2: -atoms, -, -hypernuclei nuclear structure baryon-baryon interaction in SU(3) f H-dibaryon s=3: -atom, (-,-, -hypernuclei ?) quadrupole moment of the  Hypernuclei provide a link between nuclear physics and QCD Strange Baryons in Nuclear Systems W su  du sd  dd meson vs. gluon/quark exchange

Weak baryon-baryon interaction non-mesonic weak decay of hypernuclei explore the baryon-baryon weak interaction N-N scattering w N N    s N N w  N    s N N S=0 S=1 NN N only parity violating part of weak interaction parity-conserving part masked by strong interaction only parity violating part of weak interaction parity-conserving part masked by strong interaction parity violating and parity- conserving part of weak, strangeness changing, interaction q~400 MeV/c  probes short distances parity violating and parity- conserving part of weak, strangeness changing, interaction q~400 MeV/c  probes short distances

T. Sakai, K. Shimizu, K. Yazaki Prog.Theor.Phys.Suppl. 137 (2000) H -Particle R.L. Jaffe (1977)   free coalescence  t ~ s   nuclear breeder  t ~ s neutron stars  Nuclei as Femto-Laboratory

H-particle in a nucleus  free H (see e.g. T. Yamada, NP A691 (2001) 250c; (3q)+(3q) quark cluster model ) free H-dibaryon H-dibaryon in B  =12.2 MeV B  =24.0 MeV S=-2 Nuclei and H-dibaryon States Formation of an H-particle in nuclei may modify levels in -nuclei

Contributions to intrinsic quadrupole moment of baryons One-gluon exchange Meson exchange J=1/2 baryons have no spectroscopic quadrupole moment  - Baryon: J=3/2 long mean lifetime 0.82· s only one-gluon contributions to quadrupole moment (A.J. Buchmann Z. Naturforsch. 52 (1997) ) s s s Fundamental Properties of Baryons The  quadrupole moment is an unique testcase for the quark-quark interaction

hyperfine splitting in -atom  electric quadrupole moment of  prediction Q  = ( ) fm 2 E(n=11, l=10  n=10, l=9) ~ 515 keV E Q ~ few keV for Pb spin-orbit  E ls ~ (  Z) 4 l·m  quadrupole  E Q ~ (  Z) 4 Q  m 3  spin-orbit  E ls ~ (  Z) 4 l·m  quadrupole  E Q ~ (  Z) 4 Q  m 3  Q  = fm 2 Q  = fm 2 A very Strange Atom R.M. Sternheimer, M. Goldhaber PRA 8, 2207 (1973)

2. Present Status

strangeness deposition (stopped K -, - ) tagged kaon „beam“ low momentum (T=16MeV) low background also (stopped K -, + )  neutron rich nuclei strangeness production ( +, K + ) ( -, K 0 )  BNL, KEK, (GSI?) p BEAM  1 GeV/c high beam intensity low cross section (1-10 mb/sr) q > 300 MeV/c  large p, L strangeness exchange (K _,   )(K _,   ) BNL, KEK, J-PARC low beam intensity larger cross section (100 mb/sr) magic momentum  low p, L (e,e´K + ), (,K + ) TJNAF, MAMI-C spin-flip amplitude  unnatural parity states new nuclei (p  : 10  Be) polarised beam sub-MeV resolution possible (0.3 MeV) for particle unstable states   substitutional state   non-substitutional state Single Hypernuclei

Tamura et al. Neutron number Proton number Status of Single Hypernuclei high resolution - spectroscopy with germanium detectors B(E2)~R 4  shrinkage of 6 Li core by ~20% high resolution -spectroscopy is crucial to understand the structure of hypernculei KEK, BNL

Multi-Hypernuclei are terra incognita, but they exist ! 1963: Danysz et al.  10 Be 1966: Prowse  6 He 1991: KEK-E176  13 B (or  10 Be) 2001: AGS-E906  4 H (~15); no binding energies 2001: KEK-E373  6 He (Nagara) “  10 Be (Demachi-Yanagi) NAGARA H. Takahashi et al., PRL 87, (2001) Double Hypernuclei

Interpreting B  as  bond energy one has to consider e.g. dynamical change of the core nucleus N spin-spin interaction for non-zero spin of core excited states possible if- or intermediate -nuclei are produced in excited states Q-value difficult to determine (particularly for heavy nuclei) nuclear fragments difficult to identify with usual emulsion technique new concept required  -spectroscopy! What is known? same event

3. Hypersystems in pp Interactions _

  -atoms: x-rays conversion  - (dss) p(uud)  (uds) (uds) Q = 28 MeV Conversion probability approximatly 5-10% Y. Hirata, J. Randrup et al.,  - capture

 _ (Kaidalov & Volkovitsky) quark-gluon string model s u d s d d s d s s s s    00 Use pp Interaction to produce a hyperon “beam” (t~ s) which is tagged by the antihyperon or its decay products _ General Idea

 - capture:  - p   + 28 MeV -- 3 GeV/c Kaons _    trigger p _ 2. Slowing down and capture of   in secondary target nucleus 2. Slowing down and capture of   in secondary target nucleus 1. Hyperon- antihyperon production at threshold 1. Hyperon- antihyperon production at threshold +23MeV  3.  -spectroskopy with Ge-detectors 3.  -spectroskopy with Ge-detectors  Production of Double Hypernuclei

20000 stopped  - K - beam, diamond target neutron detector arrays ( --, 12 C)  12 B + n BNL-AGS E885 few tens 2 decays of 4  H K - beam lineCylindrical Detector System 2 decays BNL-AGS E906 Captured  - per day beam/ targetdevicereactionfacility several hundreds stopped  - (K -,K + )emulsion (K -,K + ) KEK-PS E373 vertex detector + spectrometer vertex detector spectrometer,  =30 msr device 3000 „golden events“ ~ KK trigger (incl. trigger) L =2·10 32, thin target, production vertex  decay vertex p p   GSI-HESR stopped p per sec p p  K * K * K * N  K cold anti- protons <70008·10 6 /sec 5 cm 12 C (K -,K + ) JHF statusbeam/ targetreactionexperiment Competition ¯  ¯ ¯ ¯ ¯ ¯

Expected Count Rate - Ingredients (golden events) luminosity 2·10 32 cm -2 s -1  +  - cross section 2mb for pp  700 Hz p( MeV/c) p 500   + reconstruction probability 0.5 stopping and capture probability p CAP  0.20 total captured  -  3000 / day  - to nucleus conversion probability p   0.05 total  hyper nucleus production  4500 / month gamma emission/event, p   0.5 -ray peak efficiency p GE  0.1 ~7/day „golden“ -ray events ( + trigger) ~ 700/day with KK trigger high resolution -spectroscopy of double hypernuclei will be feasible

 - capture:  - p   + 28 MeV -- 5.5 GeV/c Kaons _    trigger p _ 2. Slow down and capture of   in secondary target nucleus 2. Slow down and capture of   in secondary target nucleus 1. Hyperon- antihyperon production at threshold 1. Hyperon- antihyperon production at threshold +203MeV  3.  -spectroskopy with Ge-detectors 3.  -spectroskopy with Ge-detectors Production of -Atoms

 atoms by  produktion (~35/sec) hyperfine splitting in -atom  electric quadrupole moment of  prediction Q  = ( ) fm 2 E(n=11, l=10  n=10, l=9) ~ 515 keV E Q ~ few keV for Pb taking production rate, stopping probability, capture probability and detection probability into account we expect - spin-orbit  E ls ~ (  Z) 4 l·m  quadrupole  E Q ~ (  Z) 4 Q  m 3  spin-orbit  E ls ~ (  Z) 4 l·m  quadrupole  E Q ~ (  Z) 4 Q  m 3  Q  = fm 2 Q  = fm 2 ~10 detected -transitions per day with high resolution -spectroscopy feasible A very strange Atom R.M. Sternheimer, M. Goldhaber PRA 8, 2207 (1973) Count rate estimate needs more detailed studies!

4. The Experiment

The PANDA Detector hermetic (4) high rate PID (, e, , , K, p) trigger (e, , K, D, ) compact (€) modular Elektronenkühler Injektion Kicker Septum Solid state-micro-tracker thickness ~ 3 cm High rate germanium detector

Summary Hypersystems provide a link between nuclear physics and QCD They allow to study basic properties of strongly interacting systems These unique experiments will be feasible at the GSI-HESR