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The Next Generation of Hypernucleus and Hyperatom Experiments GSI, 18.10.2000 Josef Pochodzalla Univ. Mainz.

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Presentation on theme: "The Next Generation of Hypernucleus and Hyperatom Experiments GSI, 18.10.2000 Josef Pochodzalla Univ. Mainz."— Presentation transcript:

1 The Next Generation of Hypernucleus and Hyperatom Experiments GSI, Josef Pochodzalla Univ. Mainz

2 J. Pochodzalla Quark Structure of Hyperons u u d u d d ProtonNeutron s u d s d d s d s s s s 00   ... Nucleons Hyperons

3 J. Pochodzalla Present Status of s=-1 Nuclei Until few years ago hypernuclear studies focused on (  +,K + ) or (K -,  -  reaction New tools e + e -   1020  KK tagging DA  NE)  -spectroscopy with Ge (BNL, KEK, GSI) (e,e’K + )YX(TJNAF, MAMI-c) Topics YN interaction non-mesonic weak decay  p  pn  n  nn unique chance to study baryon-baryon weak interaction ! W su  du sd  dd Weak decays...

4 J. Pochodzalla Hypernuclei and Deconfinement Manifestation of the Pauli priciple on the quark ? Quark configuration u d s Baryon configuration p n  s p s p 5 He  4 He Question...

5 J. Pochodzalla Status of Multi - Hypernuclei Multi-Hypernuclei are a terra incognita......but they exist ! 6 candidates for  -hypernuclei are observed 1963: Danysz et al. 10 Be 1966: Prowse 6 He 1991: KEK-E Be or 13 Be 1991: KEK-E176 3 non-mesonic decays  (K -,K + )   HypernucleusB  [MeV]  B  [MeV]  He10.9   0.6  Be17.7   0.4  B27.6   0.7 HypernucleusB  [MeV]  B  [MeV]  He10.9   0.6  Be17.7   0.4  B27.6  

6 J. Pochodzalla  -Nuclei as a Laboratory Hyperon-hyperon interaction H -particle R.L. Jaffe (1977) Sakai et al (nucl-th/ )... „The situation in a finite nucleus will be that the low-lying states have the character of  bound states, but that some of excited states may have strong admixture of the H-nuclear states.“

7 J. Pochodzalla  hypernuclei by  production Electric quadrupole moment of the  by hyperfine splitting in  -atoms* ) tensor forces between quarks expectation Q   = ( ) fm 2  E(ℓ=10  ℓ=9) ~ 515 keV  E Q ~ few keV for Pb The s=-3 Challange * ) C.J. Batty (1995)... “…The precision measurements of X-rays from   Pb atoms will certainly require a future generation of accelerators and probably also of physicists.“ - spin-orbit  E ℓs ~ (  Z) 4 ℓm W quadrupole  E Q ~ (  Z) 4 Q 33 m 3  spin-orbit  E ℓs ~ (  Z) 4 ℓm W quadrupole  E Q ~ (  Z) 4 Q 33 m 3  Q  = fm 2 Q  = fm 2

8 J. Pochodzalla Production of s=-2 Hypernuclei relativistic HI collisions coalescence of hyperons Bodmer (1971), Rufa et al. (1989), Schaffner et al. (1991)...  - capture:  - p   + 28 MeV (K -,K + ) KEK-PS E373, BNL-E pp annihilation at rest K. Kilian (1987), DIANA coll.  threshold - - pp  K*K* p(K*) = 285 MeV/c  K*N  K   p d  {KK  } +  - pp  K*K* p(K*) = 285 MeV/c  K*N  K   p d  {KK  } +  - _ _ _ -- 3 GeV/c 2K _  p _

9 J. Pochodzalla  - capture  -atoms: x-rays conversion  - (dss) p(uud)   (uds)  (uds)  Q = 28 MeV Conversion probability......approximatly 5-10%

10 J. Pochodzalla + -+ - + -+ - _ 2.6 GeV/c Hyperon Production For example... with L =2·10 32 cm -2 s -1  700 s -1 for a C target

11 J. Pochodzalla  - Properties  - mean life ns Consequence... minimize distance production – capture initial momentum MeV/c  range ~ few g/cm 2

12 J. PochodzallaSetup beam: 3 GeV/c,   1mm; no halo (roman pots?) internal gas target e.g. Ne, width 1mm Tracking detector for  cm thick diamond strip Si strip capillary fiber  p - -  readout gas jet

13 J. Pochodzalla Capillary Detector Glascapillaries filled with szintillator 20  m - interaction (CHORUS) Problem... fast readout possible solution :Hybrid Phototube + ALICE pixel chip Needs R&D !

14 J. Pochodzalla Gamma Spectroscopy Ge box based on VEGA type detectors segmented Clover 7 cm , 14 cm long 4 seg. clover,  PH = 1.33 MeV resolution ~ 0.5 % fast electronics under development beam p - crucial point...

15 J. Pochodzalla Count Rate - luminosity 2·10 32 cm -2 s -1     cross section 2  b for pp  700 Hz p( MeV/c) p 500    reconstruction probability 0.5 stopping and capture probability p CAP  0.20 total stopped     3000 / day    to  conversion  probability p   0.05 total  hyper nucleus production  4000 / month gamma emission/event, p   0.5  -ray peak efficiency p GE  0.1 total single line  rate ~ 5/day „golden events“ (   trigger) ~ 500/day with KK trigger

16 J. Pochodzalla 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 Observed 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 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 ¯  ¯ ¯ ¯ ¯ ¯

17 J. PochodzallaConclusion The anti-proton storage ring GSI can provide a unique facility to study strange hyperatoms and hypernuclei. Key points highest luminosity possible moderate beam quality micro tracking device high rate Germanium array Detailed spectroscopic studies of multi-strange systems will be possible. “hyperon laboratory”


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