214

octants. Each octant is longitudinally segmented into 80 layers, the first 8 (~ 14.7 Xo) comprising the electromagnetic section and the remaining 72 (~ 9.47 A/) the hadronic section. The light output from groups of 4 consecutive active layers is coupled into the same light guide, giving a total of 20 readout channels along each octant.

Fig. 1: General view of the CASTOR calorimeter construction *""•••••-...... including support. The outer plates (one omitted for clarity) constitute the support for the light guides and photomultip- liers.

This work has been supported by the Polish State Committee for Scientific Research (grant No 2P03B 121 12 and SPUB P03/016/97). References:

1. A.L.S. Angelis, J. Bartke, M.Yu. Bogolyubsky, S.N. Filippov, E. Gladysz-Dziadus, Yu.V. Kharlov, A.B. Kurepin, A.I. Maevskaya, G. Mavromanolakis, A.D. Panagiotou, S.A. Sadovsky, P. Stefanski, and Z. Wlodarczyk, Proc. 28-th Intern. Symposium on Multi- particle Dynamics, Delphi (Greece), 1998, to be published by World Scientific; A.L.S. Angelis et al., 10-th ISVHECRI, Gran Sasso, 1998, to be published in Nucl. Phys. B, Proc. Suppl.; 2. E. Gladysz-Dziadus, Yu.V. Kharlov, A.D. Panagiotou, and S.A. Sadovsky, Proc. 3-rd ICPA- QGP, Jaipur, 17-21 March 1997, eds B.C. Sinha et al., Narosa Publishing House, New Delhi, 1998, p. 554; 3. A.L.S. Angelis, J. Bartke, J. Blocki, G. Mavromanolakis, A.D. Panagiotou, and P. Zychowski, ALICE/98-46 Internal Note/CAS, CERN, 1998.

PL9902552 New Strangelet Signature and Its Relevance to the CASTOR Calorimeter

E. Gladysz-Dziadus

The hypothesis, presented in [1], to explain the anomalously long-range cascades observed in super high energy cosmic-ray events as the signs of the strange quark matter droplets, suggested the new unconventional strangelet signature. This idea has been developed and adapted to the LHC conditions [2]. It has been shown, by GEANT simulations, that the energy deposition pattern in deep calorimeters could be the spectacular and unconventional signature of different kinds of stable and unstable strangelets. Simulations of the passage of strangelets through the CASTOR calorimeter have been done for the wide spectrum of their parameters, such as:

• baryonic number Asjr = 15 — 40 • quarkchemical potential // = 600 - 1000 MeV

• energy per baryonic number Eatr = 400 - 1200 GeV 215

CASTOR calorimeter is shown to be the appropriate tool for detection of strongly penetrating objects, such as strangelets, possibly produced in the baryon-rich region in central Pb-Pb collisions at LHC energies. The CASTOR calorimeter will be sensitive to both stable and unstable strangelets for a wide range of their parameters what is very important in the context of the current experiments which are mostly sensitive only to long-lived objects. Its performance for strangelet detection can be judged from the figure below which shows the response of the calorimeter to one central Pb+Pb HIJING event, containing a strangelet of Asir = 20, Estr = 20 TeV and fi = 600 MeV.

(a) Sector with Strangelet

2 4 6 8 10 12 14 16 18 20 R.O. Layer

This work has been supported by the Polish State Committee for Scientific Research (grant No 2P03B 121 12 and SPUB P03/016/97).

References:

[1] E. Gladysz-Dziadus and Z. Wlodarczyk, ALICE/97-17, Internal Note/CAS, 1997; E. Gladysz-Dziadus and Z. Wlodarczyk, J. Phys. G: Nucl. Part. Phys. 23 (1997) 2057; [2] A.L.S. Angelis, J. Bartke, E. Gladysz-Dziadus, and Z. Wtadarczyk, Insitute of Nuclear Physics Report No 1800/PH, 1998; ALICE/98-38, Internal Note/CAS, 1998.

PL9902553 Proposal for the Experimental Study of Relativistic Hypernuclei J. Bartke, A. Filipkowski1, V. Nikitin2, and A. Parfenov2 1Soltan Institute for Nuclear Studies, Warsaw, Poland; 2Joint Institute for Nuclear Research, Dubna, Russia

Physical motivation for an experiment aimed at investigation of relativistic hypernuclei has been elaborated. Relativistic hypernuclei with energies of a few GeV per nucleon have decay lengths of the order of 10 cm what allows lifetime measurement and determination of branching ratios into various decay channels. At present such data are scarce and exist only for a few lightest hypernuclei. This is due to the fact that in most experiments the produced hypernuclei are very slow. Lifetimes and decay branching ratios of hypernuclei are very interesting from the theoretical point of view as non-mesonic decays of hypernuclei which are dominant for all but the lightest hypernuclei, result from the weak four-baryon interaction: A + p —» p+ n or A + n—>n + n. These processes are otherwise not accessible for experimental investigation being overshadowed by strong interactions. Theoretical estimates indicate that the yield of hypernuclei produced in collisions of relativistic nu- clei increases with incident energy and reaches a maximum of a few /ib in the energy range 3-4 GeV/n. Thus we propose to perform a hypernuclear experiment at the nuclotron (or the synchrophasotron) at the High Energy Laboratory (LVE) of JINR, Dubna. The scheme of the central part of the pro- posed experimental set-up: the 30 cm long vacuum decay volume with silicon trigger counters and