The HypHI Phase 0 experiment with
6
Li projectiles at 2
A
GeV on a carbon target has been performed at GSI in order to demonstrate the feasibility of hypernuclear spectroscopy with induced reaction ...of heavy ion beams. Current data analyses have shown peaks in invariant mass distributions of p + π
−
for
Λ
,
3
He+ π
−
for
3
Λ
H and
4
He + π
−
for
4
Λ
H. Lifetime values for the corresponding peaks have been also deduced, which are in good agreement with the former known values.
Performance of HPGe detectors in high magnetic fields Sanchez Lorente, A.; Achenbach, P.; Agnello, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2007, Letnik:
573, Številka:
3
Journal Article
Recenzirano
Odprti dostop
A new generation of high-resolution hypernuclear
γ
-spectroscopy experiments with high-purity germanium detectors (HPGe) are presently designed at the FINUDA spectrometer at DA
Φ
NE, the Frascati
φ
...-factory, and at
P
¯
ANDA, the
p
¯
p
hadron spectrometer at the future FAIR facility. Both, the FINUDA and
P
¯
ANDA
spectrometers are built around the target region covering a large solid angle. To maximise the detection efficiency the HPGe detectors have to be located near the target, and therefore they have to be operated in strong magnetic fields (
B
≈
1
T
). The performance of HPGe detectors in such an environment has not been well investigated so far. In the present work VEGA and EUROBALL Cluster HPGe detectors were tested in the field provided by the ALADiN magnet at GSI. No significant degradation of the energy resolution was found, and a change in the rise time distribution of the pulses from preamplifiers was observed. A correlation between rise time and pulse height was observed and is used to correct the measured energy, recovering the energy resolution almost completely. Moreover, no problems in the electronics due to the magnetic field were observed.
.
The energy centroids and integrated strengths of Gamow-Teller transitions in the
and electron-capture decay are analyzed for nuclei whose proton number
Z
and neutron number
N
are restricted to 44
Z
...50 and 50
N
58 . The analysis is based on data measured both with high-resolution
-ray spectrometry and total
-ray absorption techniques. The dependence of the considered quantities on the relative neutron excess are established after taking into account the effects due to the Coulomb interaction and mean-field level occupancies. An extrapolation of this dependence to the lightest known tin isotopes is used to estimate the decay characteristics of
100
Sn and
101
Sn . The values extrapolated for the half-lives of
100
Sn and
101
Sn agree with experimental data. Using the extrapolated values together with shell model predictions, the
Q
values for the electron-capture decay of
100
Sn is evaluated. The quenching factor for
and the electron-capture decay of the nuclei under consideration here is established to be 0.56(2) with a possible weak dependence on
N
-
Z
.
Results of the HypHI Phase 0 experiment with the reaction of 6Li+12C at 2 A GeV are summarised. Invariant mass distributions as well as the lifetime measurements for 3ΛH and 4ΛH are discussed. The ...lifetime values for both the hypernuclei are respectively observed to be 183+42−32 ps and 140+48−33 ps, being significantly shorter than those of the Λ-hyperon. Statistical analyses of existing lifetime data for 3ΛH up to 2014 confirm a significantly short lifetime of 3ΛH, which is not explained by present models. Observed hypernuclear production cross section values for 3ΛH and 4ΛH are also summarised. In addition, observed signals for the final states of d+π− and t+π− are discussed. All the discussions on the results of the HypHI Phase 0 experiment in this article are based on 1–4. We also present a new proposed experiment with the FRS (FRagment Separator) at GSI (FAIR Phase 0) to improve the precision of the hypernuclear spectroscopy with peripheral heavy ion induced reactions.
We have developed a compact detector for measuring beam particles using plastic scintillators readout through Multi-Pixel Photon Counters, which is employed for hypernuclear measurements in the ...WASA-FRS experiment at GSI. The Time-of-Flight resolution of the newly-developed detector has been investigated in relation to the overvoltage with respect to the breakdown voltage, a maximum counting rate of approximately 3×106/s per segment, and a maximum beam charge of Z = 6. The evaluated Time-of-Flight resolutions between the neighboring segments of the detector range from 44.6±1.3 ps to 100.3±3.6 ps (σ) depending on the segment, overvoltage values, and beam intensity. It is also observed that the Time-of-Flight resolution is inversely correlated to the beam atomic charge (Z).
The WASA-FRS project at GSI and its perspective Saito, T.R.; Achenbach, P.; Alfaki, H. Alibrahim ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
09/2023, Letnik:
542
Journal Article
Recenzirano
Odprti dostop
A novel technique to study bound states of exotic hadrons in subatomic nuclei, such as hypernuclei and mesic nuclei, has been developed by employing the Fragment Separator FRS and the WASA central ...detector at GSI. Two experiments, S447 for studying light hypernuclei, especially hypertriton and a Λnn bound state, and S490 for searching for η’ mesic-nuclei, were recently performed. Data analyses are currently in progress, and light charged particles such as protons and π± are clearly observed and identified in the both experiments. For S447, light nuclear fragments that can also be residual nuclei from decays of hypernuclei of interests have been analysed by the FRS, and a momentum resolution, Δp/p, of 5×10−4 has been achieved. Further data analyses are to be completed. The WASA-FRS project will be continued and extended with the FRS at FAIR Phase 0, and upgrading of the WASA magnet and detectors is currently in progress. Furthermore, construction of a larger detector system with the Super-FRS at FAIR Phase 1 is also under consideration.
The PANDA collaboration at FAIR, Germany, will employ antiproton annihilations to investigate yet undiscovered charm-mesons and glueballs aiming to unravel the origin of hadronic masses. A ...multi-purpose detector for tracking, calorimetry and particle identification is presently being developed to run at high luminosities providing up to 2.107 interactions/s. A trigger-less data-acquisition system will be employed with sub-detectors continuously providing data from incoming physics events. This paper describes readout electronics and the treatment of the digitised preamplifier signal for the Electromagnetic Calorimeter. The use of a Sampling ADC in the readout allows to achieve the design goals, namely a large dynamic range from 1 MeV to 10 GeV, a count-rate dependent low trigger threshold of about 1-3 MeV, and a time resolution better than 1 ns.
The first excited 2+ state of 36Ca has been identified by its γ-decay, exploiting the two-step fragmentation technique at the FRS-RISING setup at GSI. This is the heaviest Tz=−2 nucleus in the Segré ...chart in which a γ-decay of an excited state has been observed. A stable beam of 40Ca at 420AMeV impinged on a primary 9Be target. Out of the secondary beam of fragmentation products, 37Ca was separated by the FRS and struck on a second 9Be target at the final focus of the FRS. The energy for the 21+ decay of 36Ca was determined to be 3015(16) keV, which is 276 keV lower than in its T=2 mirror 36S. This mirror energy difference (MED) is discussed in the framework of shell model calculations using a 16O core, the sd shell isospin symmetric interaction USD and experimental single-particle energies from 17O and 17F. The results show that the MED within the sd shell provide a sensitive test for the evolution of the N, Z=14,16 subshell gaps towards the driplines. Especially the N, Z=16 gap is determined by Thomas–Ehrman shift in the A=17, T=1/2 isospin doublet, while Coulomb effects are found to have marginal influence.
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