The recent determination of the partial decay widths for the one-proton and the two-nucleon induced Non-Mesonic Weak Decay of Λ-Hypernuclei in the A=5–16 range permitted to reconstruct the full ...pattern of decay widths for 5ΛHe and 11ΛB. A consistency check on 12ΛC decay widths confirms the validity of the adopted method.
Umbilical cord blood (UCB) as an allogeneic transplant source is generally limited to units with pre-cryopreservation total nucleated cell (TNC) doses ⩾2.5 × 10(7) NC/kg. We prospectively ...investigated single UCB transplantation, with cord units as low as 1 × 10(7) NC/kg, all processed with post-thaw albumin-dextran dilution. We transplanted 104 adult patients with 84% having relapsed/refractory disease. The median TNC dose was 2.1 × 10(7) NC/kg (range: 1.0-4.4 × 10(7)) and median CD34+ cell dose was 1.0 × 10(5)/kg (range: 0.0-3.7 × 10(5)/kg). Post-manipulation cell recovery and viability were 96% and 99%, respectively. Median times to neutrophil and platelet engraftment were 16 and 43 days, respectively. Univariate factors predicting neutrophil engraftment included TNC (P=0.03) and CD34+ cell dose (P=0.01). CD34+ dose predicted platelet engraftment (P<0.001). In multivariate analysis, CD34+ dose remained significant for neutrophil and platelet engraftment (P<0.0001 and P<0.0001, respectively). The 100-day and 1-year overall survival were 70% and 46%, respectively (95% confidence interval: 36%-56% at 1 year). The subset transplanted with 1-1.5 × 10(7) NC/kg had similar 100-day and 1-year survivals of 73% and 45%, respectively. Single-unit UCB transplantation using small units, processed as described, leads to favorable engraftment and acceptable outcomes in poor prognosis patients. CD34+ cell dose (⩾1.5 × 10(5)/kg) helps predict faster engraftment and can aid in graft selection.
Previous studies of proton and neutron spectra from Non-Mesonic Weak Decay of eight Λ-Hypernuclei (A=5–16) have been revisited. New values of the ratio of the two-nucleon and the one-proton induced ...decay widths, Γ2N/Γp, are obtained from single proton spectra, Γ2N/Γp=0.50±0.24, and from neutron and proton coincidence spectra, Γ2N/Γp=0.36±0.14stat−0.04sys+0.05sys, in full agreement with previously published ones. With these values, a method is developed to extract the one-proton induced decay width in units of the free Λ decay width, Γp/ΓΛ, without resorting to Intra Nuclear Cascade models but by exploiting only experimental data, under the assumption of a linear dependence on A of the Final State Interaction contribution. This is the first systematic determination ever done and it agrees within the errors with recent theoretical calculations.
The FINUDA experiment has recently completed an extensive study of the weak decay of p-shell Λ hypernuclei including both Mesonic and Non-Mesonic modes. The present paper is focused on the study of ...proton spectra from Non-Mesonic Weak Decay, both single and in coincidence with a neutron, which has triggered the investigation of the two nucleon-induced ΛNN→nNN decay channel. Furthermore thanks to the excellent performance of FINUDA in terms of long-term instrumental stability and fully reliable reconstruction and analysis programs it has been possible to isolate and kinematically reconstruct single events related to the occurrence of rare physical processes. Three events corresponding quite safely to the observation of the 2N-induced Non-Mesonic Weak Decay were analyzed and fully reconstructed. They are the experimental evidence for such a process, up to now conjectured only by indirect measurements. Discussion of the results is outlined.
The decay of Λ-hypernuclei without π emission, known as Non-Mesonic Weak Decay (NMWD), gives an effective tool to investigate ΔS=1 four-baryon interactions. It was theoretically suggested that the ...two-nucleon induced mechanism could play a substantial role in reproducing the observed NMWD decay rates and nucleon spectra, but at present no direct evidence of such a mechanism has been obtained. The FINUDA experiment, exploiting the possibility to detect both charged and neutral particles coming from the hypernucleus decay, has allowed us to deduce the relative weight of the two nucleon induced decay rate to the total NMWD rate. The value of Γ2N/ΓNMWD=0.21±0.07stat−0.02sys+0.03sys has been deduced, well consistent with the previous determinations.
This Letter is concerned with the study of the Kstop−A→π±Σ∓A′ reaction in p-shell nuclei, i.e., 6,7Li, 9Be, 13C and 16O. The π±Σ∓/Kstop− emission rates are reported as a function of A. These rates ...are discussed in comparison with previous findings. The ratio π−Σ+/π+Σ− in p-shell nuclei is found to depart largely from that on hydrogen, which provides support for large in-medium effects possibly generated by the sub-threshold Λ(1405). The continuum momentum spectra of prompt pions and free sigmas are also discussed as well as the π±Σ∓ missing mass behavior and the link with the reaction mechanism. The apparatus used for the investigation is the FINUDA spectrometer operating at the DAΦNEϕ-factory (LNF-INFN, Italy).
A new generation of high-resolution hypernuclear γ-spectroscopy experiments using high-purity germanium (HPGe) detectors is presently designed for the FINUDA spectrometer at DAΦNE, the Frascati ...Φ-factory, and for PANDA, the p–p¯ hadron spectrometer at the future FAIR facility. In both spectrometers the HPGe detectors have to be operated in strong magnetic fields. In this paper we report on a series of measurements performed on a HPGe detector inserted in a magnetic field of intensity up to 2.5T, the highest ever reached for operations with a HPGe, and with different orientations of the detector's axis with respect to field direction. A significant worsening of the energy resolution was found, but with a moderate loss of the efficiency. The most relevant features of the peak shapes, described by bi-Gaussian functions, are parametrized in terms of field intensity and energy: this allows to correct the spectra measured in magnetic field and to recover the energy resolution almost completely.
Recent results reported by experiments with relativistic (heavy) ions have raised again the question whether the lifetime of HΛ3 is very close to the lifetime of the free Λ hyperon. An updated ...careful analysis of all the existing experimental data shows that it is not, contrary to theoretical calculations. A similar conclusion can be drawn for the neighbor HΛ4. A clear cut high precision measurement performed with the straightforward method of time delay spectra is however lacking and it is eagerly needed. The idea of using the (π−,K0) charge-exchange associated production reaction on targets of liquid 3,4He is discussed. A possible realization exploiting a large part of existing facilities at J-PARC is presented. A measurement with a 5% precision seems within reach with a modest effort and in a reasonable amount of time. The same set-up would also serve very well for the measurement of the lifetime of several neutron-rich Λ-hypernuclei of the p-shell, in particular of BΛ12. More importantly, the Weak Decay partial widths Γπ−, Γp and Γπ0 could be simultaneously determined in order to confirm their predicted strong variation with mass number, A, due to nuclear structure effects.
In the J-PARC E27 experiment, we search for a
K
−
pp
bound state via the
d
(
π
+
,
K
+
) reaction at 1.7 GeV/
c
at the K1.8 beam line. The binding energy and decay width of the
K
−
pp
bound state can ...be obtained in the missing mass measurement with a good energy resolution of 2 MeV/
c
2
. A range counter array (RCA) was constructed to detect the two high-momentum protons from the
K
−
pp
decay and to reduce the background such as quasi-free hyperon production. Recently, we have carried out a pilot run in June, 2012. The
d
(
π
+
,
K
+
) missing-mass spectrum has been obtained for the first time. In this report, an overview of the E27 experiment and a preliminary result on this pilot run are presented.
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