Study of the kaonic nuclear clusters at DAΦNE: the AMADEUS experiment Dorel Pietreanu LNF - INFN, Via. E. Fermi 40, 00044 Frascati (Roma), Italy On behalf of the AMADEUS Collaborations LNF Spring School “Bruno Touschek”, May 15th-19th, 2006 LNF Spring School “Bruno Touschek”, May 2006

Antikaonic Matter At DAFNE: an Experiment Unraveling Spectroscopy LNF Spring School “Bruno Touschek”, May, 2006

           information concerning a modification of the kaon mass and of the KN interaction in the nuclear medium => interesting and important from the viewpoint of spontaneous and explicit symmetry breaking of QCD            information on a transition from the hadronic phase to a quark-gluon phase => changes of vacuum properties of QCD and quark condensate            kaon condensation in nuclear matter => implications on astrophysics: neutron stars, strange stars nuclear dynamics under extreme conditions (nuclear compressibility, etc) could be investigated Important impacts in fundamental physics LNF Spring School “Bruno Touschek”, May, 2006

Exploring dense nuclear states with K- bound states LNF Spring School “Bruno Touschek”, May, 2006

Current and future planned experiments FINUDA at DAFNE KEK: E549 - to confirm the existence of the two strange tribaryons observed in E471 E570 J-PARC (LOI06; LOI10) – K-induced reaction in flight GSI (FOPI) – nucleus-nucleus and proton –nucleus collision LNF Spring School “Bruno Touschek”, May, 2006

Y. Akaishi & T. Yamazaki, Phys. Rev. C 65 (2002) 044005 First experimental indications: E471 Experiment Results 4He(K-stopped, n) and 4He(K-stopped, p) missing mass spectra (M. Iwasaki et al., nucl-ex/0310018 v2) S0(3115): M = 3117 +3.8-2.0(sys)+/-0.9 (stat) G< 21.6 MeV, B= -194 MeV with respect to K-+p+n+n rest mass Predicted NOT to exist! (B~20 MeV; G~100 MeV) S+(3140): M = 3117 +3.8-2.0(sys)+/-2.3 (stat) G< 21.6 MeV, B= -169 MeV with respect to K-+p+p+n rest mass Predicted with B ~ 110 MeV M. Iwasaki et al., NIM A 473 (2001) 286 Y. Akaishi & T. Yamazaki, Phys. Rev. C 65 (2002) 044005 LNF Spring School “Bruno Touschek”, May, 2006

Production mechanisms of DBKNS: 1) Stopped K- reactions on light nuclei, with ejection of a proton or a neutron as spectators 2)  In-flight K- reactions: - Knock-out reactions (K-, N) where one nucleon is knocked out in the formation stage; - (K-, π-) reactions in proton-rich systems to produce exotic bound nuclear states on unbound systems. 3) Protons (3.5 – 4.5 GeV) on a deuteron target for the production of K–pp detected in a 4 detector. 4) The identification of clusters as residual fragments (“K fragments”) in heavy ion collisions via the invariant mass of their decay products. Identification and study of DBKNS: - Formation -> missing mass Decay -> invariant mass -> Spectroscopy! LNF Spring School “Bruno Touschek”, May, 2006

Features of the experimental setup The complete study of the characteristic features of the kaonic bound nuclear systems requires knowledge of: binding energy, level width and partial widths, angular momentum, isospin, sizes, densities, etc. This can be done by simultaneously observing the production stage of the K--clusters via missing mass spectroscopy, and their decay products since their momentum correlations contain information on the internal structure of the exotic system. It is therefore necessary to use a 4π dedicated detector capable of detecting all particles created in both the formation and decay of the K-clusters. LNF Spring School “Bruno Touschek”, May, 2006

K- + 4He -> n + (K-ppn) np- Ld Lpn S0pn S-pp pp- (~64%) Lg Features of the experimental setup The decay process K- + 4He -> n + (K-ppn) np- Ld Lpn S0pn S-pp pp- (~64%) Lg np0 (~36%) pp- np0 n(~500 MeV/c) 2pnp- 2p;n;g;p- 1p;2n;p0;g 2p;n;p- 1p;2n;p0 p;d;p- n;d;p0 LNF Spring School “Bruno Touschek”, May, 2006

Features of the experimental setup Decay process The exotic states are expected to predominantly decay into final states containing  and S hyperons and protons, neutrons, deuterons or larger systems of nucleons. The most important feature of a detector is therefore the reconstruction capability for  and S hyperons from the invariant mass of their decay into nucleon +  and/or g. This implies good particle identification for these particles and their decay products. From this data, frame-invariant Dalitz plots can be constructed, which are expected to reflect the size and density of the initial exotic state. LNF Spring School “Bruno Touschek”, May, 2006

The KLOE detector The detector satisfying all these features => Performance of the KLOE 4p detector: fully checked and exploited in the numerous measurements done already by KLOE; studies of processes with BR of < 10-3 (10-6) acceptance 96% DC: sp/p ~ 0.4% Spatial resolution of vertices in DC: 3 mm dE/dx capacity for particle ID implemented ECAL dE/Eg ~ 5.7%/E1/2 st= (54/E1/2 + 50) ps Ks->p+p- at 0.8 MeV/c2 p0 mass resolution to 2-3 % (reconstruction) Resol. for n of 500 MeV/c ~ 3% LNF Spring School “Bruno Touschek”, May, 2006

AMADEUS integration in KLOE: first drawing EMC KLOE – Drift Chamber Possible setup for AMADEUS within KLOE: Cryogenic target Inner tracker Kaon trigger LNF Spring School “Bruno Touschek”, May, 2006

Preliminary design: AMADEUS setup at KLOE LNF Spring School “Bruno Touschek”, May, 2006

AMADEUS Experimental programme Measurements to be performed: The most fundamental system which we plan to study are the kaonic dibaryon states of ppK- and npK-, which are favorable produced using a 3He gas target in 3He(K-, n/p) reactions. Their masses including their total width will be determined by neutron and proton energy measurements respectively. Exclusive measurements of their decays allow to extract further information: size/density, angular momentum, ... A similar programme is planned for kaonic 3-baryon states, populated in reactions using a 4He gas target. Furthermore we plan to extend these studies systematically over a broad range of nuclear targets starting by Li, B and Be. LNF Spring School “Bruno Touschek”, May, 2006

http://www. lnf. infn. it/esperimenti/siddharta/LOI_AMADEUS_March2006 http://www.lnf.infn.it/esperimenti/siddharta/LOI_AMADEUS_March2006.pdf LNF Spring School “Bruno Touschek”, May, 2006

Thank you! LNF Spring School “Bruno Touschek”, May, 2006

3He ---> 3HeK- shrinkage !! rc ~ 4 -10 r0 Explore cold and dense nuclear states (Dote et al. 2002) LNF Spring School “Bruno Touschek”, May, 2006

Features of the experimental setup Formation process: K- + 4He -> p + (K-pnn); p ~ 550 MeV/c K- + 4He -> n + (K-ppn); n ~ 510 MeV/c Exotic nuclear states in light nuclei produced with (K-, N) reactions at rest will be observed by the energy distribution of the ejected protons and neutrons via the missing mass spectra of the (K-, p) and (K-, n) reactions. The setup should be capable to measure: Outgoing protons up to 600 MeV/c Outgoing neutrons up to 600 MeV/c in a 4π acceptance detector, with good efficiency and resolution. LNF Spring School “Bruno Touschek”, May, 2006

Pre-experiment: PROPOSAL to KLOE First actions towards AMADEUS Pre-experiment: PROPOSAL to KLOE The DC of KLOE  seen as an active target (4He) where => some K- stop => DBKNS DC K-pnn K- p LNF Spring School “Bruno Touschek”, May, 2006

Pre-experiment: PROPOSAL to KLOE First actions towards AMADEUS Pre-experiment: PROPOSAL to KLOE A preliminary Monte Carlo simulation shows that with 2 fb-1 one might have due to K- stopped in the He gas of the DC: > 1500 events of -> the BEST measurement in the world > 500 events of AMADEUS group -> willing to help KLOE in data analysis K- + 4He -> p + (K-pnn); p ~ 550 MeV/c K- + 4He -> n + (K-ppn); n ~ 510 MeV/c LNF Spring School “Bruno Touschek”, May, 2006

K-ppn  ° + d p + - K-ppn  ° + p + n p + - Pre-experiment: PROPOSAL to KLOE 4He + K-  K-ppn + n K-ppn  ° + d p + - K-ppn  ° + p + n p + - d n - n p - p - p energy [MeV] LNF Spring School “Bruno Touschek”, May, 2006

AMADEUS Experimental programme By observing momentum correlation in the three-body decay channel, such as pppK-  +p+p or ppnK-  +p+n, one will get information, using the correlation pattern in the Dalitz plane, of the size, density and the angular momentum of the involved kaonic cluster.  all decay products have to be identified  their 4-momenta have to be determined LNF Spring School “Bruno Touschek”, May, 2006

Conclusions   As far as the experimental setup is concerned, the 4p KLOE detector, implemented for AMADEUS program, operated in DAFNE2, satisfies the requirements to study the characteristic features of the K-nuclear clusters, which must consists both in observing the production stage of a K-nuclear clusters and detecting the decay products. DANE2 can become the world-scientific pole to study the K- induced processes at rest, which were indicated as the more direct way to investigate the clusters in nuclear matter. First steps towards the realization: Monte Carlo intensive simulations Measurement (KLOE+SIDDHARTA) of KLOE calorimeter for n-efficiency Feasibility of AMADEUS in KLOE Possibility to participate to KLOE2 – new parts LNF Spring School “Bruno Touschek”, May, 2006

Kaonic nuclear clusters: short introduction Features and identification of the setup and the experimental programme First steps towards AMADEUS Conclusions LNF Spring School “Bruno Touschek”, May, 2006

LNF Spring School “Bruno Touschek”, May, 2006