K-K-K-K- p n=25 n=2 n=1 From kaonic atoms to kaonic nuclei with DA  NE November th LNF Scientific Committee C. Curceanu and J. Zmeskal DEAR/SIDDHARTA Collaboration Proposal of an international facility at DANE2

(pre) Letter of Intent The case of deeply bound kaonic nuclear states Proposal of an international facility at DA  NE2 September 2005 DEAR/SIDDHARTA Collaboration Manifestation of interest from Institutions of: - Austria - Canada - France - Germany - Hungary - Italy - Japan - Poland - Romania - Russia - Sweden - USA - … Letter of Intent -> Spring th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Antikaonic Matter At DA  NE: an Experiment Unraveling Spectroscopy AMADEUS 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Contents 1) Brief sketch of the scientific case of kaonic nuclear clusters 2) From kaonic atoms to K - –nuclear bound states 3) Current and future experiments => the unique features of DA  NE2 5) Features and identification of the setup and the experimental programme 6) First steps towards AMADEUS 7) Formation of an international collaboration 8) Conclusions 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

A new paradigm in strangeness nuclear physics, with important consequences in fundamental physics, is represented by the recently observed Deeply bound Kaonic Nuclear states whose first experimental indications are being produced at - KEK and - LNF - GSI - BNL => cold and dense nuclear system 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

KN interaction Until 1997: Confusing situation (part due to KH puzzle) 1997 KpX experiment at KEK Iwasaki et al. PRL(1997): K - p atom shift:  E 1s “ repulsive-type ”, Indicating the K - p interaction is strongly attractive 2002 DEAR results -> PRL 94, (2005) Consistent with the view that  (1405): 1s bound state of K - p Scattering data (no data at low energy) 2002: Akaishi-Yamazaki constructed “ Nuclear K bound states in light nuclei ” Y. Akaishi & T. Yamazaki, Phys. Rev. C 65 (2002) th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Kaonic Nuclear Bound States Believed ( E B Akaishi-Yamazaki (2002) predicted: - K - -p interaction so strong that it - might shrinks nuclei --> deeper bound states - deep enough that: the main decay channel KN-->  closed - strongly (deeply) bound states E B > 100 MeV: narrow bound states (  <10 MeV) 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

First experimental indications: E471 Experiment Results 4 He(K - stopped, n) and 4 He(K - stopped, p) missing mass spectra (M. Iwasaki et al., nucl-ex/ v2) S 0 (3115): M = (sys)+/-0.9 (stat)  < 21.6 MeV, B= -194 MeV with respect to K - +p+n+n rest mass Predicted NOT to exist! (B~20 MeV;  ~100 MeV) S + (3140): M = (sys)+/-2.3 (stat)  < 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) th LNF Scientific Committee CC,JZ / Nov. 29, 2005

 c ~  0  Explore cold and dense nuclear states 3 He ---> 3 HeK - shrinkage !! (AMD method Dote et al. 2002) 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Exploring dense nuclear states with K - bound states 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

modification of the kaon mass and of the KN interaction in the nuclear medium spontaneous and explicit symmetry breaking of QCD transition from the hadronic phase to a quark-gluon phasevacuum properties of QCD and quark condensate kaon condensation astrophysics: neutron stars, strange stars nuclear dynamics under extreme conditions - 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 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

From low-energy KN interactions to K-nuclear bound states “to what extent does our present knowledge of low-energy KN interactions support such expectations (the hypothesis of narrow K-nuclear states introduced by Akaishi and Yamazaki) ?” (W. Weise, nucl-th/ ) 1) the low-energy KN scattering data 2) the kaonic hydrogen shift of the ground state 3) the binding energy and decay width of  (1405), asserted to be an I=0 quasi-bound state of KN. Rate of formation and additional constraints: 4) Kaonic helium transitions The pillars of the existence of narrow K-nuclear states: 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

. Future (expected) progress in the field: 1) Kaonic Hydrogen and kaonic deuterium (SIDDHARTA: pb -1 ) -> to ~ eV => I=0 and I=1 KN scattering lengths 2) Low-energy scattering: A new facility at DA  NE2 to study K - nuclear clusters with a 4  detector, may include in its scientific program a K ± scattering on nucleons/nuclei to build up a high quality set of data. 3)  (1405) Precise KN measurements at threshold (SIDDHARTA) will substantially improve the knowledge of the sub-threshold KN dynamics and contribute to clarify the nature of  (1405). More information can come from the measurement of two-body branching ratios in K - absorption at rest, which is precisely the kind of reactions to be studied in the new facility at DA  NE2. Specifically, one can investigate in- medium corrections to the branching ratios in K - absorption at rest and their effect on the charged  ± spectrum. 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

. 4) Kaonic Helium: SIDDHARTA (200 pb -1 ) - the rate + additional constraints Crucial information about the formation of a specific deeply bound kaonic nuclear state (the K - 3 He system) -> depends on the X ray transitions in the K - 4 He atom. There are three experiments which observed kaonic helium atomic transitions from 3d to 2p levels, giving an experimental average value for the width  = 55 ± 34 eV. => the formation branching ratio turns out about 2%; right now -> E570 at KEK. The theoretical widths are around = 2-4 eV. Analogous discrepancy between experiments and optical models calculations does exists for the shifts. This is what is dubbed “the kaonic helium puzzle”. Preliminary Monte Carlo simulations, performed for the SIDDHARTA setup with a gaseous 4 He target show that a measurement with a precision of eV can be performed at DA  NE with about 200 pb -1 of integrated luminosity. Similar estimations hold for the 3 He case. The capability to detect kaonic helium X-rays transitions might turn out extremely useful in implementing an X-ray trigger to reduce the background in the measurement of kaonic nuclear states by capture at rest on 4 He in a new dedicated facility at DA  NE2. 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Deeply Bound Kaonic Nuclear States Deeply Bound Kaonic Nuclear States KN low-energy scattering Kaonic Hydrogen and deuterium  (1405) 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

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! 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Current and future planned experiments FINUDA at DA  NE KEK: E549 E570 J-PARC (LOI06; LOI10) GSI (FOPI) 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Why DA  NE2 is a good place to study kaonic nuclear clusters (1) The future experiments in Japan (J-PARC) will produce kaonic nuclear states only with K - -induced reactions in-flight (=1  2 GeV/c), either in (K -, N) or in (K -,  - ) processes. The alternative approach, followed at GSI, is represented by proton-nucleus collisions at beam energies close to the strangeness production threshold and nucleus-nucleus collisions It follows, that a dedicated facility at DA  NE2 can become THE scientific pole for studying kaonic nuclear states with K — induced reaction at rest. 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Why DA  NE2 is a good place to study kaonic nuclear clusters (2) The salient features of DA  NE2 are: - Low-momentum (127 MeV/c) medium intensity charged kaons:  1200/s at L  cm -2 s -1 ; - Low momentum spread (<0.1%); - K  pairs produced in a back-to-back topology; - hadronic background intrinsically low – differently from an extracted beam. 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

How DA  NE2 characteristics can be exploited at best for the study of strongly bound kaonic nuclear states? 1) possibility to use either gaseous targets (as proven by DEAR) or thin targets (as proven by FINUDA). 2) Reduced neutron background generated by negative pion absorption (E47) exactly in the area of interest. The yield of these background neutrons depends on the equivalent g/cm 2 of the target, namely on density and thickness, and on the materials put around the target itself. 3) The back-to-back topology which characterizes K - production, can be used to trigger on (K -, K + )-pairs, so selecting K - induced events. 4) Another trigger system might be implemented by taking advantage of the X rays emitted in the decay of the kaonic atom, created in the initial stage of the process. 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

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 momenta, 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. 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Features of the experimental setup Formation process: 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. K He -> n + (K - ppn); n ~ 510 MeV/c K He -> p + (K - pnn); p ~ 550 MeV/c 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

K He -> n + (K - ppn) n-n- dd  pn  0 pn  - pp p  - (~64%)  n  0 (~36%) p-p- n0n0 n0n0 p-p- n(~500 MeV/c) 2pn  - n(~500 MeV/c) 2p;n;  ;  - 1p;2n;  0 ;  n(~500 MeV/c) 2p;n;  - 1p;2n;  0 n(~500 MeV/c) p;d;  - n;d;  0 Features of the exp. setup: the decay process 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Monte Carlo simulation: P(   ) GeV/c P(p) GeV/c P(  ) GeV/c P(n) GeV/c n(~500 MeV/c) +  np ppn  -  -> p  - ; n < 600 MeV/c;  - < 300 MeV/c 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Features of the experimental setup Decay process The exotic states are expected to predominantly decay into final states containing  and  hyperons and protons, neutrons, deuterons or larger systems of nucleons. The most important feature of a detector is therefore the reconstruction capability for  and  hyperons from the invariant mass of their decay into nucleon +  and/or . This implies good particle identification for these particles and their decay products. 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Features of the experimental setup Decay process From this data, frame-invariant Dalitz plots can be constructed, which are expected to reflect the size and density of the initial exotic state. Special attention must be paid to two-body correlations in a Dalitz plane, which may lead to a fake effect in an invariant mass spectrum  + p, which might be confused with the genuine mass of an exotic strange dibarion K - pp   + p if all the three particles are not detected. 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Density distribution of K nuclear clusters JZ / Nov. 29, 2005  by observing the momentum correlation in their 3-body decay products (P. Kienle, Y. Akaishi, T. Yamazaki to be published in Phys. Lett. B) K - ppn   + p + n 31th LNF Scientific CommitteeCC,JZ / Nov. 29, 2005

The detector satisfying all these features => The KLOE detector Performance of the KLOE 4  detector: -fully checked and exploited in the numerous measurements done already by KLOE; -studies of processes with BR of < (10 -6 ) -acceptance 96% -DC:  p /p ~ 0.4% -Spatial resolution of vertices in DC: 3 mm -dE/dx capacity for particle ID implemented -ECAL dE/E  ~ 5.7%/E 1/2  t= (54/E 1/2 + 50) ps -K s ->  +  - at 0.8 MeV/c 2  0 mass resolution to 2-3 % (reconstruction) -Resol. for n of 500 MeV/c ~ 3% …… 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

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 3 He gas target in 3 He(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 4 He gas target. Furthermore we plan to extend these studies systematically over a broad range of nuclear targets starting by Li, B and Be. 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

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 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

The scientific programme of the nuclear cluster facility will be discussed in dedicated meetings and in the dedicated Workshop: “Exotic hadronic atoms, deeply bound nuclear states and antihydrogen: present results and future” to be held at ECT* (Trento), on June 19-24, 2006 Organizers: Catalina Curceanu (Petrascu) – LNF – INFN, Frascati (Italy) coordinator Eberhard Widmann, Stefan Meyer Institut für subatomare Physik - Austrian Academy of Sciences, Vienna (Austria) Akaki Rusetsky, Univ. Bonn, Germany 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

First actions towards AMADEUS 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

First actions towards AMADEUS KLOE calorimeter efficiency for neutrons a)Monte Carlo simple GEANT simulation => to be continued =>   eV/c > 20% (~30%) b) KLOE+SIDDHARTA tests on KLOE calorimeter prototype (long and short modules) on neutron beam: -n_TOF at CERN -BTF at LNF (?) 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

First actions towards AMADEUS -at n_TOF at CERN – if available in 2006 Neutrons from 1 eV to 150 MeV energy -possibility to collimate the beam -10 –100 MeV ~10 6 n/pulse -dE/E (100 MeV) ~ 2% Prepare request to Research Board 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

First actions towards AMADEUS -at BTF (LNF) Neutrons from photoproduction (-> 800 MeV electrons) - Feasibility study (working group) 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

First actions towards AMADEUS AMADEUS integration in KLOE: first drawing to be continued with: -setup integration: gaseous and solid targets -Physics  Scientific program 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Search for anti-kaon clusters with KLOE 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005 KLOE – EMC KLOE – Drift Chamber Possible setup for AMADEUS within KLOE: Cryogenic target Inner tracker Kaon trigger

Preliminary design: AMADEUS setup at KLOE a first draft of the interaction region DEAR beam pipe Inner tracker Kaon trigger Cryogenic target cell K+K+ K-K- 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Preliminary extrapolations AMADEUS on KLOE setup confronted with KEK E471 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

E471 Experiment Results 4 He(K - stopped, n) and 4 He(K - stopped, p) missing mass spectra M. Iwasaki et al., nucl-ex/ v2 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

E471 features The results were obtained for a total number of about 2 x 10 8 stopped negative kaons inside the liquid helium target. - acceptance for detection of charged particles: 34%; - detection efficiency for neutron: 36%; - solid angle for the neutron/proton detector: 8%. With these conditions, the number of events in the missing mass spectra of the two reactions, are: - about 450 events in the (K -, p) reaction for the S 0 (3115) neutral tribaryon, with a signal/background ratio about 1/10; - about 120 events in the (K -, n) reaction for the S + (3140) charged tribaryon, with a signal/background ration about 1/10; The formation ratios for the considered reactions turned out to be of the order of ~ th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Extrapolation from KEK to DA  NE2 - more than 70% of kaons generated by  –decay can be stopped, with an optimized degrader, inside a gaseous helium target. For a yearly integrated luminosity of about 10 fb -1, the total numbers of kaons generated in about 2 months (same time interval as at KEK) will be ~ 2 x 10 9 and ~ 1.4 x 10 9 will stop inside the target. For a dedicated 4  detector we assume the following figures of merit: - acceptance for the detection of charged particles: 90%; - detection efficiency for neutrons detector: 30%; - solid angle for the neutron/proton detector: 90%. Expected events in the case of a 4 He target: - about in the (K -, p) reaction for the neutral tribaryon K - pnn - about in the (K -, n) reaction for the charged tribaryon K - ppn 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

First actions towards AMADEUS Pre-experiment: PROPOSAL to KLOE The DC of KLOE  seen as an active target ( 4 He) where => some K - stop => DBKNS DC K- K- p K - pnn 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

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 He -> n + (K - ppn); n ~ 510 MeV/c K He -> p + (K - pnn); p ~ 550 MeV/c 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Even more: K - ppn   ° + p + n p +  - energy [MeV] d -- p K - ppn   ° + d p +  - 4He + K-  K-ppn + n n n p p -- -- 31th LNF Scientific CommitteeCC,JZ / Nov. 29, 2005

Formation of an international collaboration The Proposal is presented by physicists of the international collaboration DEAR/SIDDHARTA, which are working on DA  NE since 1996 and where they will be still engaged for the next three years. To the DEAR/SIDDHARTA collaboration belong 11 institutions from 8 different countries. The interest raised in the international community by kaonic atoms physics at DA  NE involved, since the beginning, also scientists from outside Europe, like Japan, USA and Canada, which actively participated and are participating to the experiments at DA  NE. =>“hard core” of an international collaboration does already exist. 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Formation of an international collaboration Other considerations support the strong appealing of the new initiative and consequently a potentially large interested community: The DA  NE2 with AMADEUS would represent the only facility in the world where K — induced reactions at rest are studied. Moreover, after the GSI merging into FAIR, Frascati would be the only laboratory in Europe to go along this line of research. The fact to become the European counterpart with respect to the Japanese programmes at J-PARC reinforces the plan to apply to the Seventh Framework Programme of EU to obtain a substantial economical support both for developments of detectors and for the upgrading of the actual machine. 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005 Dec , 2005 Workshop on “ Antikaon Mediated Bound Systems – Doorway to Kaon Condensation in Neutron Stars ”

The scientific case of the study of deeply bound kaonic nuclear states deals with one of the most important, yet unsolved, problems in hadron physics: how the hadron masses and hadron interaction change in the nuclear medium and what is the structure of cold dense hadronic matter. After the shutdown of KEK in December 2005, two facilities will be active in the field: J-PARC in Japan, and GSI (FOPI) in Europe. The first one will produce kaonic nuclear clusters with K - -induced reactions in flight. GSI will follow, before being absorbed in the new complex of facilities FAIR, an alternative approach, represented by nucleus-nucleus and proton-nucleon collisions. 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. 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005 Conclusions (1)

Conclusions (2) As far as the experimental setup is concerned, the 4  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. 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 Spring > Letter of Intent 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Deeply Bound Kaonic Nuclear States KN low-energy scattering Kaonic Hydrogen and deuterium  (1405) From kaonic atoms to kaonic-nuclei Continuity and innovation 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

First experimental indications: E471 Experiment Results 4 He(K - stopped, n) and 4 He(K - stopped, p) missing mass spectra (M. Iwasaki et al., nucl-ex/ v2) S 0 (3115): M = (sys)+/-0.9 (stat)  < 21.6 MeV, B= -194 MeV with respect to K - +p+n+n rest mass Predicted NOT to exist! (B~20 MeV;  ~100 MeV) S + (3140): M = (sys)+/-2.3 (stat)  < 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) th LNF Scientific Committee CC,JZ / Nov. 29, 2005

Monte Carlo simulation: phase space P(   ) GeV/c P(p) GeV/c P(   ) GeV/c P(p) GeV/c n(~500 MeV/c) +   pp ppn  -  - -> n  - ; n < 500 MeV/c;  - < 300 MeV/c 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

AMADEUS Experimental programme Is based on precision spectroscopy studies of light kaonic nuclei, as function of their baryon number A and isospin T. In addition, heavier nuclear targets will be studied. The first objective is to determine the quantum numbers (spin, parity, isospin) of all states, including excited ones, and their energies. A precise measurement of the energies of a T=1 multiplet would give its Coulomb energy difference (about 4 MeV) and thus information on the size of kaonic nuclei. The challenge of this programme is to reach the necessary accuracy in the determination of the mass differences of the multiplet. 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

AMADEUS Experimental programme The study of the spin-orbit interaction of the strange tribaryon system [(NNN)K], by measuring the spin-orbit splitting (0p 1/2 – 0p 3/2 ) which is predicted to be as large as 60 MeV (for small size kaonic nuclei). Important information on the structure of kaonic clusters is contained in their total and partial decay widths. Until now, only on upper limit of  = 21 MeV is known for a kaonic tribaryon state and no information on partial decay channels is available. For an accurate measurement of the total width of kaonic nuclei an energy resolution of ~MeV or better is required. 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005

As far as the signal/background ratio (S/B) is concerned, the neutrons produced by low-energy negative pion absorption, will be strongly reduced at DA  NE2, as previously shown. Moreover, the implementation of a (K +, K - )-pair trigger and of an X-rays trigger from kaonic atoms decay, should improve S/B by more than a factor 2. 31th LNF Scientific Committee CC,JZ / Nov. 29, 2005