36th Meeting of LNF Scientific Committee 21 May 2008 FINUDA Analysis Report and Extension Proposal π- π- p μ+ Vincenzo Lucherini - LNF
FINUDA physics program • - LHYPERNUCLEAR SPECTROSCOPY • essential tool for testing : • theoretical models of L-N potentials • single particle nuclear model predictions • bound states with strangeness SIMULTANEOUSLY • - HYPERNUCLEAR DECAYS • study of baryon-baryon weak processes in nuclear matter: LpN and LNNN • Neutron-rich hypernuclei and ON DIFFERENT NUCLEI and, moreover: • SEARCH FOR: • K- multi-nucleon absorption • Deeply bound kaonic nuclei Window of opportunity in this and next year, before the start of J-PARC
Progress in detector calibrations Correction for track angle of attacks on LMDC Relevant for positive tracks as the muons (K+stopnm+) used to check spectrometer resolution even w. before odd w. after even w. odd w.
Progress in Particle Identification Contamination in deuteron selection , as example d d d p π+μ+ p Contamination in triton selection d t Suppression of MIP and p contamination on d and t discrimination with 3 and 4 layers !
FINUDA can simultaneously detect prompt p-and p from Hyp. N.M.W. decay and measure their spectra K− + 12C → 12ΛC + π− Hypernuclei spectroscopy Proton from Hyp. decay p p- Prompt p- from Hyp. formation Incl. p-p coinc. Prompt π-spectrum in coincidence with a proton Protonspectrum in coincidence with a π- from the Hyp. ground state. Hypernuclei decay
Hypernuclear spectroscopy: FINUDA versus al. - e C 12 - K L stop M.Agnelloet al., Phys. Lett. B 622 (2005) 35 Thin target DE ~ 1.3 MeVFWHM C H. Hotchi et al., Phys. Rev. C 64 (2001) 044302 FINUDA 12 L 12C(K-,π-)12C DE ~ 1.5 MeVFWHM KEK M. Iodiceet al., PRL. 99 (2007) 052501 DE ~ 0.7 MeV FWHM TJNAF FINUDA has the lowest resolution with hadronic probe 12C(,e’K+) 12 B L No access to Hyp. decays 12C(π+,K+)12C
16O Hypernuclear Spectroscopy D2O Counts/0.5 MeV/c p- momentum (GeV/c) p- inclusive spectrum from the D2O target clearly shows all the Hypernuclear levels expected from 16OL. The right and left spectrum differ in the quality cuts for track selection.
Non-mesonic weak decays: proton spectra from the decay of Hypernuclear ground states measured to the lowest energy ever done. First measurement for7ΛLi 5ΛHe 7ΛLi 12ΛC First time 5ΛHe: FINUDA vs KEK 12ΛC: FINUDA vs KEK Phys. Lett. B 597 (2004) 249 Phys. Lett. B 597 (2004) 249 FINUDA, Nucl. Phys. A 622 (2008) 151
Access to the non-mesonic weak decay proton spectra of 5ΛHe from two different nuclei: not only from 6Li but also from 7Li (first time) andsimultaneously π- spectrum in coincidence with one proton: 6Li T. 5ΛHe FINUDA, Nucl. Phys. A 622 (2008) 151 π- spectrum in coincidence with one proton: 7Li T. 7LiL g.s.
N.M.W. D: Firstdirect measurement of Rp (proton yield per prompt p) FINUDA, Nucl. Phys. A 622 (2008) 151
5ΛHe Theoretical curve FINUDA proton spectra N.M.W.D: Comparison with theoretical calculations • Kolmogorov-Smirnov comp. test : 12ΛC : probability P=0.5 at a confidence level of 5% Low compatibility • 5ΛHe : probability of P=0.65 at a confidence level of 75% 12ΛC Theoretical curve (Phys. Rev. C 69 054603 ) FINUDA proton spectra KEK (Phys. Rev. C 69 054603 ) Realiable data provided for the first time in an extedend energy and A range to better understand FSI effects and L-two-nucleons interactions. KEK FINUDA, Nucl. Phys. A 622 (2008) 151
Neutron-rich hypernuclei FINDA can access to two production mechanisms (inside nuclei): • strangeness + double charge exchange • K- + p →Λ + π0 • →π0 + p →n + π+ • 2) strangeness exchange with Λ-Σ coupling • K- + p →Σ- + π+ • →Σ- + p →Λ + n Two step reaction low yield expected Possible signature in p+ spectrum following K- absorption
Search for neutron rich hypernuclei: 6Li and 7Li targets 2003-04 data taking: p+inclusive spectra 2006-07 data taking: p+ spectra in coincidence with p- (decay) PLB 640 (2006)145 The procedure is assessed, more statistics needed
Mesonic Decay of Hypernuclei • The two main decay mechanisms of a inside a hypernucleus are: • Mesonic Weak decay, similarly to a free • Non Mesonic Weak Decay (NMWD): a weak interaction -Nucleon(s) • In a Mesonic weak decay: • p-B.R. 63.9% (Г-) • n0B.R. 35.8% (Г0) • nucleons (and p) are emitted with a low momentum q ~ 100MeV/c • The mesonic weak decay is suppressed in nuclei due to the Pauli blocking of the (low momwntum) nucleon in the final state • The suppression is expected to increase as A increases. • In light nuclei, as 6Li and 7Li ,a seazable contribution should however be present: can FINUDA detect it?
The capability of FINUDA to detect p-down to 70-80 MeV/c opens the possibility to search for Hyp. Mesonic decays
Decay FINUDA and 7LLi - 5LHe Production and Mesonic Decay 4LH 4He + p– (132.9 MeV/c) 3LH 3He + p– (~114 MeV/c) Detection of prompt p- in coincidence with p- of low momentum from mesonic decay of the hypernucleus levels
FINUDA and 7LLi - 5LHe Mesonic Decay Spectrum of Inclusive p- K- + 7Li 7LLi + p– (276 MeV/c) K- + 7Li 5LHe +d+ p–or 5LHe +p+n + p– prompt p- Negative pion spectrum in coincidence with negative prompt pions in the region of 5ΛHe and 7ΛLi(270-280 MeV/c). 7ΛLi 5ΛHe (MeV) Spectrum of p- in coincidence Mesonic decay Counts / 2 MeV/c Short, low momentum p- tracks reconstructed thanks to the Si-Vertex performances pp- (MeV/c)
Hypernuclear Physics: FINUDA can simultaneously provide the full pattern: prompt p-, andpandp-from Hyp. decay and measure their spectra 7ΛLi Hypernuclear spectroscopy Incl. p-p- coinc. p-p coinc. Spectrum of p- in coincidene Protonspectrum in coincidence with a π- from the Hyp. ground state. Mesonic Hyp. decay Counts / 2 MeV/c p- NMW Hypernuclei decay pp- (MeV/c)
For K--Nucleus interactions Λ identification is a crucial item FINUDA FRONTAL VIEW VERTEX REGION Straw tubes Wire chambers Vertex detector Beam pipe π- π- L p π- K- π- p K+ μ+ μ+ Plastic Scintillators FINUDAis able to reconstruct the L vertex also outside the active tracking volumes
Λ relevant for FINUDA physics are produced by K-stopped coincidence p- p without Lambda vertex reconstruction s = 2.6 MeV/c2 coincidence p- p with Lambda vertex reconstruction s = 1.7 MeV/c2 Quasi-free L production K--multi nucleon absorption K-stopped turn out to be an abundant source of high momentum L, and FINUDA turns out to be properly tuned just in that momentum region
- 6Li d a p K- 3He+K- d n FINUDA: study of 6Li(K-,Ld)X • Λd invariant mass • Use of 6Li target: low background • 6Li is a well known [α+d] cluster • Bump observed at Md= 3251 MeV, d=37 MeV • 25 events in the peak, statistical significance3.9σ FINUDA Coll., PLB 654 (2007) 80
K-stop6Li Λ d n dspect The events in the bump (3250 MeV/c2) are strongly correlated in angle and momenta 6Li 2006-07 2003-04 Λ momenta for events in the invariant mass bump cluster around the 500-700 MeV/c region These findings are confirmed with better statistics in the last data taking
Study of A(K-,Lt)X Data Taking 2006-2007 6Li, 7Li, 9Be targets • π-,p invariant mass in • coincidence with a t Λ signal identified background free Λt pairs found with a surprisingly strong and clean correlation in angle and momenta! Λ momenta for events in coincidence with t cluster around the 500-700 MeV/c region Submitted to Phys. Lett. B, April 2008
Study of A(K-,Lp)X FINUDA Coll., PRL 94(2005)212303 B = 115+6-5 (stat)+3-4 (sys)MeV = 67+14-11(stat)+2-3 (sys)MeV Yield ≈0.1%/stopped K- 6Li 7Li 2006-07 Λ momenta for events in the invariant mass bump cluster around the 500-700 MeV/c region
FINUDA capability to study K--multi-nucleon absorption Quasi-free L production L associated to K- multi-nucleon absorption L momenta associated with the bumps in Lp, Ld inv. mass or correlated with t Whatever be the true explanation of the tricky results of FINUDA (K- -NN, or -NNN, or -NNNN interaction, hint of kaonic bound states , ...) , it is a fact that FINUDA couples its excellent p.id. with a L detection acceptance best in the most interesting region
Extension proposal - Motivations The Physics that FINUDA can explore has been discussed in many Workshops, and Conferences and has been item of several papers, resulting ones of the hottest topics today debated in Nuclear Physics . FINUDA is still the only apparatus with proven capabilities to give a full picture of the Hypernuclear processes: formation and decay (both mesonic and non mesonic). FINUDA has a superb p.id. for charged partcicles as heavy as tritons. FINUDA acceptance is ideally tuned in the region of the L momenta associated with K- -multinucleon interactions (around 500-700 MeV/c) were unexpected, intringuing or possibly exotic phenomena seem to appear In the present and next year, with J-PARC not yet started at full regime, FINUDA has a unique window of opportunity (even with the luminosities of the last run). A 6-10 times increase in statistics with respect to the past is desirable for selected nuclei to settle several topics in Hypernuclear Physics (spectroscopy, decay, neutron rich) and in K- multinucleon interaction. The target choice of: 2x12C, 4x6Li, plus the 2x 28Si of the ISIM modules in the antiboost side can fulfill this request, with 3 fb-1.
FINUDA ROLLED IN DAFNE UPGRADED: Overview FINUDA is mechanically compatible with the configuration of upgraded DAFNE
FINUDA IN DAFNE UPGRADED: Beam Pipe Region The present Be window can be adapted, in a specialized factory, to the DAFNE upgraded beam pipe of smaller diameter.
FINUDA INSTALLATION ON DAFNE UPGRADED FINUDA ROLL-IN FINUDA has already done twice the ROLL-IN (and the ROLL-OUT) operations. The time needed was of 2.5 months the first time and 2 months the second (the beam pipe was already inserted). The procedures are well known and there is experience for them: the provision for a third FINUDA ROLL-IN is then of 2.5 months, considering that a new beam pipe has to be inserted (and, of course, previouly procured). SWAP of DAFNE UPGRADED To install in the FINUDA side the interaction region, it is necessary to swap the present DAFNE configuration and install the four superconducting compensating solenoids.This is a complex task for the Accelerator Division. The present configuration was mounted in 5.5 months, in the summer-fall 2007. A reasonable time estimation for the swapping seems to be 4 months. Overall installation time The operations to Roll-in FINUDA can, for the main part, proceed in parallel with those to swap the machine: hence an overall installation time can be estimated to be 4.5 months (including contingencies and not parallelized operations).
UPGRADE OF FINUDA DAQ Scope of the DAQ upgrade is to maintain the live time to the same level than in the previous data taking, foreseeing a peak istantaneous Luminosity of 2x1032 cm-1s-2 and 4x1032 cm-1s-2 The goal can be achieved by an extensive parallelization by optical fibers of the readout system and by implementing, in case of the increased Luminosity scenario, a second level trigger. The hardware for such implementations has already been financed by the Commission III and the work, already started, will last several months.
CONCLUSIONS We think that everibody has well clear the firm groundness of the Scientific Case for a third FINUDA data taking and the realistic and optimal time window for it. We also think that the FINUDA Collaboration has always demonstrated, for what was in its power, to fulfill the assigned tasks, to respect the deadlines, to produce excellent physical results on the forefront of its field of activity and to be a reliable partner with everybody it has interacted. We hence consider to deserve the right to know, as soon as the situation around DAFNE will be clarified,If FINUDA will be allowed, or not, to have a new data taking after the completition of the SIDDHARTA one.