ABSTRACT The FINUDA experiment has recently completed an extensive study of the weak decay of p-s... more ABSTRACT The FINUDA experiment has recently completed an extensive study of the weak decay of p-shell Lambda-hypernuclei including both mesonic and non-mesonic modes. Charged mesonic decay rates have been determined based on the analysis of pi(-) kinetic energy spectra, never measured before. The study of proton spectra from non-mesonic weak decay for p-shell hypernuclei, both single and in coincidence with a neutron, has triggered the investigation of the two-nucleon induced Lambda NN --> nNN decay channel: its weight has been evaluated to be Gamma(2)/Gamma(NM) = 0.21 +/- 0.07(stat-0.02sys)(+0.03sys). Finally, a direct experimental evidence of the occurrence of the weak reaction Lambda np --> nnp in nuclei is presented for the first time. Three events have been found which can be attributed to Li-7(Lambda) and Be-9(Lambda) two-nucleon induced non-mesonic weak decay; the kinematical analysis is discussed here.
... Italy P. Montagna Dipartimento di Fisica Teorica e Nucleare, Universita'di Pavia and INF... more ... Italy P. Montagna Dipartimento di Fisica Teorica e Nucleare, Universita'di Pavia and INFN Sezione di Pavia, via Bassi 6, Pavia, Italy ... 113-0033, Japan N. Mirfakhrai Department of Physics, Shahid Behesty University, 19834 Teheran, Iran G. Beer University of Victoria, Finnerty Rd ...
From the study of the annihilation at rest ~7p + K*K$,,T~F'T-the production rates of the r]( 1440... more From the study of the annihilation at rest ~7p + K*K$,,T~F'T-the production rates of the r]( 1440) + K*K$rI were obtained for three different hydrogen target densities: liquid, gaseous at NTP and at low pressure (5 mbar). The rate values are: f7(1m) (LH) = (6.010.5) . 10e4, f q(l~) (NTP) = (2.9 f 0.4) . lop4 and f V(~~~) (5 mbar) = (1.0 f 0.2) . 10p4. From these results, the density dependence of the annihilation fraction from the 'SO protonium level can be extracted directly.
The inelastic charge exchange reaction (K + , K 0 ) on 7 Li has been experimentally investigated ... more The inelastic charge exchange reaction (K + , K 0 ) on 7 Li has been experimentally investigated close to threshold with the FINUDA spectrometer at the e + e − collider DA NE by searching for K 0 S decays. It is the first time that this process has been studied at such low momentum. An upper limit of 2.0 mb (at 95% confidence level) has been measured for the total cross section.
† This paper is dedicated to the memory of V. Filippini Nuclear Physics A 752 (2005) 139c-144c 03... more † This paper is dedicated to the memory of V. Filippini Nuclear Physics A 752 (2005) 139c-144c 0375-9474/$ -see front matter
The FINUDA experiment collected data to study the hypernuclear production on different targets, t... more The FINUDA experiment collected data to study the hypernuclear production on different targets, that is 6 Li, 7 Li, 9 Be, 12 C, 13 C, D 2 O, 27 Al and 51 V. The hypernuclei formation was achieved through the strangeness-exchange reaction
In spring 2003 the FINUDA detector was installed at the φ factory DA NE in the Laboratori Naziona... more In spring 2003 the FINUDA detector was installed at the φ factory DA NE in the Laboratori Nazionali di Frascati of INFN (Italy). In October 2003 the commissioning of the apparatus was accomplished and the first data taking started with a set of nuclear targets 6 Li, 7 Li, nat C, 27 Al, 51 V. The data collection will continue until a total integrated luminosity of 250 pb −1 is recorded. Light and medium A hypernuclei will be abundantly produced by the strangeness exchange reaction induced by the stopped K − coming from the decay of φ(1020) mesons.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1995
The characteristics and performances of a large time of flight detector which is composed by two ... more The characteristics and performances of a large time of flight detector which is composed by two scintillator barrels, installed between the poles of an axial field magnet as part of the OBELIX spectrometer, are described. The associated electronics, data acquisition system and analysis technique used in the system are discussed in details. The importance of the detector for trigger purposes and for the comprehension of the full event is shown.
The European Physical Journal C - Particles and Fields, 2004
The hadronic annihilation branching-ratios in quasi-two-body final states have been obtained from... more The hadronic annihilation branching-ratios in quasi-two-body final states have been obtained from the observation of the reactionspp→π + π − π 0 , K + K − π 0 , K ± π ∓ K 0 at rest in hydrogen targets at different densities. The enhancement or suppression of specific hadronic channels connected to dynamical selection rules is observed in the production of different resonances both in protonium S and P-waves, systematically investigated for the first time. Besides the well known ρ(770)π and a2(1320)π enhancement from 3 S1 and 1 S0 partial waves, the dominance of one isospin source in K * (892)K production, well established from S-waves, is confirmed also in P-waves ( 1 S0, I = 0; 3 S1, I = 1; 1 P1, I = 0; 3 P1, I = 0; 3 P2, I = 1). In addition, the experimental data clearly show a strong suppression of φ(1020)π and a0(980)π final states from P-wave which has a remarkable coincidence with K * (892)K pattern production.
The FINUDA experiment studies the Λ-hypernuclei formation and decay using the reaction (K − stop ... more The FINUDA experiment studies the Λ-hypernuclei formation and decay using the reaction (K − stop , π − ) induced by the low-momentum K − from the deacy of the φ-meson produced at the (e + , e − ) collider DAφNE at the Laboratory Nazionali di Frascati of INFN. In this paper we present new data on the proton spectra following the weak decay of 12 Λ C.
... di Fisica del Politecnico di Torino, Via Giuria 1, I-10125 Torino, Italy INFN Sezione di Tori... more ... di Fisica del Politecnico di Torino, Via Giuria 1, I-10125 Torino, Italy INFN Sezione di Torino, Via Giuria 1, I-10125 Torino, Italy INFN Sezione di Pavia, Via Bassi 6, Pavia, Italy G. BEER University of Victoria, Finnerty Rd., Victoria, Canada INFN Sezione di Pavia, Via Bassi 6, Pavia ...
ABSTRACT The FINUDA experiment has recently completed an extensive study of the weak decay of p-s... more ABSTRACT The FINUDA experiment has recently completed an extensive study of the weak decay of p-shell Lambda-hypernuclei including both mesonic and non-mesonic modes. Charged mesonic decay rates have been determined based on the analysis of pi(-) kinetic energy spectra, never measured before. The study of proton spectra from non-mesonic weak decay for p-shell hypernuclei, both single and in coincidence with a neutron, has triggered the investigation of the two-nucleon induced Lambda NN --> nNN decay channel: its weight has been evaluated to be Gamma(2)/Gamma(NM) = 0.21 +/- 0.07(stat-0.02sys)(+0.03sys). Finally, a direct experimental evidence of the occurrence of the weak reaction Lambda np --> nnp in nuclei is presented for the first time. Three events have been found which can be attributed to Li-7(Lambda) and Be-9(Lambda) two-nucleon induced non-mesonic weak decay; the kinematical analysis is discussed here.
... Italy P. Montagna Dipartimento di Fisica Teorica e Nucleare, Universita'di Pavia and INF... more ... Italy P. Montagna Dipartimento di Fisica Teorica e Nucleare, Universita'di Pavia and INFN Sezione di Pavia, via Bassi 6, Pavia, Italy ... 113-0033, Japan N. Mirfakhrai Department of Physics, Shahid Behesty University, 19834 Teheran, Iran G. Beer University of Victoria, Finnerty Rd ...
From the study of the annihilation at rest ~7p + K*K$,,T~F'T-the production rates of the r]( 1440... more From the study of the annihilation at rest ~7p + K*K$,,T~F'T-the production rates of the r]( 1440) + K*K$rI were obtained for three different hydrogen target densities: liquid, gaseous at NTP and at low pressure (5 mbar). The rate values are: f7(1m) (LH) = (6.010.5) . 10e4, f q(l~) (NTP) = (2.9 f 0.4) . lop4 and f V(~~~) (5 mbar) = (1.0 f 0.2) . 10p4. From these results, the density dependence of the annihilation fraction from the 'SO protonium level can be extracted directly.
The inelastic charge exchange reaction (K + , K 0 ) on 7 Li has been experimentally investigated ... more The inelastic charge exchange reaction (K + , K 0 ) on 7 Li has been experimentally investigated close to threshold with the FINUDA spectrometer at the e + e − collider DA NE by searching for K 0 S decays. It is the first time that this process has been studied at such low momentum. An upper limit of 2.0 mb (at 95% confidence level) has been measured for the total cross section.
† This paper is dedicated to the memory of V. Filippini Nuclear Physics A 752 (2005) 139c-144c 03... more † This paper is dedicated to the memory of V. Filippini Nuclear Physics A 752 (2005) 139c-144c 0375-9474/$ -see front matter
The FINUDA experiment collected data to study the hypernuclear production on different targets, t... more The FINUDA experiment collected data to study the hypernuclear production on different targets, that is 6 Li, 7 Li, 9 Be, 12 C, 13 C, D 2 O, 27 Al and 51 V. The hypernuclei formation was achieved through the strangeness-exchange reaction
In spring 2003 the FINUDA detector was installed at the φ factory DA NE in the Laboratori Naziona... more In spring 2003 the FINUDA detector was installed at the φ factory DA NE in the Laboratori Nazionali di Frascati of INFN (Italy). In October 2003 the commissioning of the apparatus was accomplished and the first data taking started with a set of nuclear targets 6 Li, 7 Li, nat C, 27 Al, 51 V. The data collection will continue until a total integrated luminosity of 250 pb −1 is recorded. Light and medium A hypernuclei will be abundantly produced by the strangeness exchange reaction induced by the stopped K − coming from the decay of φ(1020) mesons.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1995
The characteristics and performances of a large time of flight detector which is composed by two ... more The characteristics and performances of a large time of flight detector which is composed by two scintillator barrels, installed between the poles of an axial field magnet as part of the OBELIX spectrometer, are described. The associated electronics, data acquisition system and analysis technique used in the system are discussed in details. The importance of the detector for trigger purposes and for the comprehension of the full event is shown.
The European Physical Journal C - Particles and Fields, 2004
The hadronic annihilation branching-ratios in quasi-two-body final states have been obtained from... more The hadronic annihilation branching-ratios in quasi-two-body final states have been obtained from the observation of the reactionspp→π + π − π 0 , K + K − π 0 , K ± π ∓ K 0 at rest in hydrogen targets at different densities. The enhancement or suppression of specific hadronic channels connected to dynamical selection rules is observed in the production of different resonances both in protonium S and P-waves, systematically investigated for the first time. Besides the well known ρ(770)π and a2(1320)π enhancement from 3 S1 and 1 S0 partial waves, the dominance of one isospin source in K * (892)K production, well established from S-waves, is confirmed also in P-waves ( 1 S0, I = 0; 3 S1, I = 1; 1 P1, I = 0; 3 P1, I = 0; 3 P2, I = 1). In addition, the experimental data clearly show a strong suppression of φ(1020)π and a0(980)π final states from P-wave which has a remarkable coincidence with K * (892)K pattern production.
The FINUDA experiment studies the Λ-hypernuclei formation and decay using the reaction (K − stop ... more The FINUDA experiment studies the Λ-hypernuclei formation and decay using the reaction (K − stop , π − ) induced by the low-momentum K − from the deacy of the φ-meson produced at the (e + , e − ) collider DAφNE at the Laboratory Nazionali di Frascati of INFN. In this paper we present new data on the proton spectra following the weak decay of 12 Λ C.
... di Fisica del Politecnico di Torino, Via Giuria 1, I-10125 Torino, Italy INFN Sezione di Tori... more ... di Fisica del Politecnico di Torino, Via Giuria 1, I-10125 Torino, Italy INFN Sezione di Torino, Via Giuria 1, I-10125 Torino, Italy INFN Sezione di Pavia, Via Bassi 6, Pavia, Italy G. BEER University of Victoria, Finnerty Rd., Victoria, Canada INFN Sezione di Pavia, Via Bassi 6, Pavia ...
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