.
The Phase-Imaging Ion-Cyclotron-Resonance (PI-ICR) technique has been commissioned at the JYFLTRAP double Penning trap mass spectrometer. This technique is based on projecting the ion motion in the ...Penning trap onto a position-sensitive multichannel-plate ion detector. Mass measurements of stable
85
Rb
+
and
87
Rb
+
ions with well-known mass values show that relative uncertainties
Δ
m
/
m
≤
7
·
10
-
10
are possible to reach with the PI-ICR technique at JYFLTRAP. The significant improvement both in resolving power and in precision compared to the conventional Time-of-Flight Ion Cyclotron Resonance technique will enable measurements of close-lying isomeric states and of more exotic isotopes as well as ultra-high precision measurements required,
e.g.
, for neutrino physics. In addition, a new phase-dependent cleaning method based on the differences in the accumulated cyclotron motion phases has been demonstrated with short-lived
127
In
+
and
127m
In
+
ions.
Towards commissioning the new IGISOL-4 facility Moore, I.D.; Eronen, T.; Gorelov, D. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
12/2013, Letnik:
317
Journal Article
Recenzirano
•The commissioning of the new IGISOL-4 facility.•First successful implantation of neutron-deficient Pd.•In-jet laser ionization of copper demonstrated.
The Ion Guide Isotope Separator On-Line ...facility at the Accelerator Laboratory of the University of Jyväskylä is currently being re-commissioned as IGISOL-4 in a new experimental hall. Access to intense beams of protons and deuterons from a new MCC30/15 cyclotron, with continued possibility to deliver heavy-ion beams from the K=130MeV cyclotron, offers extensive opportunities for long periods of fundamental experimental research, developments and applications. A new layout of beam lines with a considerable increase in floor space offers new modes of operation at the facility, as well as a possibility to incorporate more complex detector setups. We present a general overview of IGISOL-4 and the current status of several projects, including the collinear laser spectroscopy station and the future of neutron-induced fission. Recent milestones from the first commissioning experiments are presented.
The
98
Mo double-beta decay
Q
-value has been measured, and the corresponding nuclear matrix elements of neutrinoless double-beta (
0
ν
β
β
) decay and the standard two-neutrino double-beta (
2
ν
β
β
...) decay have been provided by nuclear theory. The double-beta decay
Q
-value has been determined as
Q
β
β
=
113.668
(
68
)
keV using the JYFLTRAP Penning trap mass spectrometer. It is in agreement with the literature value,
Q
β
β
=
109
(
6
)
keV, but almost 90 times more precise. Based on the measured
Q
-value, precise phase-space factors for
2
ν
β
β
decay and
0
ν
β
β
decay, needed in the half-life predictions, have been calculated. Furthermore, the involved nuclear matrix elements have been computed in the proton–neutron quasiparticle random-phase approximation (pnQRPA) and the microscopic interacting boson model (IBM-2) frameworks. Finally, predictions for the
2
ν
β
β
decay are given, suggesting a much longer half-life than for the currently observed cases.
Abstract The first direct determination of the ground-state-to-ground-state $${\beta ^{-}}$$ β - -decay Q -value of $$^{77}$$ 77 As to $$^{77}$$ 77 Se was performed by measuring their atomic mass ...difference utilizing the double Penning trap mass spectrometer, JYFLTRAP. The resulting Q -value is 684.463(70) keV, representing a remarkable 24-fold improvement in precision compared to the value reported in the most recent Atomic Mass Evaluation (AME2020). With the significant reduction of the uncertainty of the ground-state-to-ground-state Q -value and knowledge of the excitation energies in $$^{77}$$ 77 Se from $$\gamma $$ γ -ray spectroscopy, the ground-state-to-excited-state Q -value of the transition $$^{77}$$ 77 As (3/2 $$^{-}$$ - , ground state) $$\rightarrow $$ → $$^{77}$$ 77 Se $$^{*}$$ ∗ (5/2 $$^{+}$$ + , 680.1035(17) keV) was refined to be 4.360(70) keV. We confirm that this potential low Q -value $${\beta ^{-}}$$ β - -decay transition for neutrino mass determination is energetically allowed at a confidence level of about 60 $$\sigma $$ σ . Nuclear shell-model calculations with two well-established effective Hamiltonians were used to estimate the partial half-life for the low Q -value transition. The half-life was found to be of the order of 10 $$^{9}$$ 9 years for this first-forbidden non-unique transition. Since the half-life of $$^{77}$$ 77 As is only $$\approx $$ ≈ 2 days, usage of it as source for rare-event experiments searching for the electron antineutrino mass would be challenging.
•An overview of the FRS Ion Catcher experiment at GSI is given.•The FRS Ion Catcher consists of the FRS, a cryogenic stopping cell, an RF quadrupole-based beam transport and diagnostics unit and a ...multiple-reflection time-of-flight mass spectrometer.•Off-line tests of the stopping cell with 219Rn ions.•First on-line operation of a stopping cell for exotic nuclei at cryogenic temperatures.•First mass measurements of heavy projectile fragments using a multiple-reflection time-of-flight mass spectrometer.
At the FRS Ion Catcher at GSI, projectile and fission fragments are produced at relativistic energies, separated in-flight, range-focused, slowed down and thermalized in a cryogenic stopping cell. A multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) is used to perform direct mass measurements and to provide an isobarically clean beam for further experiments, such as mass-selected decay spectroscopy. A versatile RF quadrupole transport and diagnostics unit guides the ions from the stopping cell to the MR-TOF-MS, provides differential pumping, ion identification and includes reference ion sources. The FRS Ion Catcher serves as a test facility for the Low-Energy Branch of the Super-FRS at the Facility for Antiproton and Ion Research (FAIR), where the cryogenic stopping cell and the MR-TOF-MS will be key devices for the research with stopped projectile and fission fragments that will be performed with the experiments MATS and LaSpec. Off-line tests of the stopping cell yield a combined ion survival and extraction efficiency for 219Rn ions of about 30% and an extraction time of about 25ms. The stopping cell and the MR-TOF-MS were commissioned on-line as part of the FRS Ion Catcher. For the first time, a stopping cell for exotic nuclei was operated on-line at cryogenic temperatures. Using a gas density almost two times higher than ever reached before for a stopping cell with RF ion repelling structures, various 238U projectile fragments were thermalized and extracted with very high efficiency. Direct mass measurements of projectile fragments were performed with the MR-TOF-MS, among them the nuclide 213Rn with a half-life of 19.5ms only.
Precision mass measurements of 104Y, 106Zr, 104,104m,109Nb, and 111,112Mo have been performed with the JYFLTRAP double Penning trap mass spectrometer at the Ion Guide Isotope Separator On-Line ...facility. The order of the long-lived states in 104Nb was unambiguously established. The trend in two-neutron separation energies around the N=66 neutron midshell appeared to be steeper with respect to the Atomic Mass Evaluation 2020 extrapolations for the 39Y and 40Zr isotopic chains and less steep for the 41Nb chain, indicating a possible gap opening around Z=40. The experimental results were compared to the BSkG2 model calculations performed with and without vibrational and rotational corrections. All of them predict two low-lying minima for 106Zr. While the unaltered BSkG2 model fails to predict the trend in two-neutron separation energies, selecting the more deformed minima in calculations and removing the vibrational correction, the calculations are more in line with experimental data. The same is also true for the 21+ excitation energies and differences in charge radii in the Zr isotopes. The results stress the importance of improved treatment of collective corrections in large-scale models and further development of beyond-mean-field techniques.
To enhance the production of medium-heavy, neutron-rich nuclei, and to facilitate measurements of independent yields of neutron-induced fission, a proton-to-neutron converter and a dedicated ion ...guide for neutron-induced fission have been developed for the IGISOL facility at the University of Jyväskylä. The ion guide holds the fissionable targets, and the fission products emerging from the targets are collected in helium gas and transported to the downstream experimental stations. A computer model, based on a combination of MCNPX for modeling the neutron production, the fission code GEF, and GEANT4 for the transport of the fission products, was developed. The model will be used to improve the setup with respect to the production and collection of fission products. In this paper we benchmark the model by comparing simulations to a measurement in which fission products were implanted in foils located at different positions in the ion guide. In addition, the products from neutron activation in the titanium foil and the uranium targets are studied. The result suggests that the neutron flux at the high-energy part of the neutron spectrum is overestimated by approximately 40
%
. However, the transportation of fission products in the uranium targets agrees with the experiment within 10
%
. Furthermore, the simulated transportation of fission products in the helium gas achieves almost perfect agreement with the measurement. Hence, we conclude that the model, after correction for the neutron flux, is well suited for optimization studies of future ion guide designs.
A Penning trap has been installed for isobaric beam purification at the IGISOL-facility at the University of Jyväskylä. In this paper, the technical details of this new device together with results ...of the first tests are presented. The mass resolving power, depending on the excitation parameters and the ion species, can be as high as 145
000 and the total transmission has been determined to be 17%. In addition, it is shown that with this experimental setup it is possible to measure atomic masses up to
A=120 with accuracies of approximately
50
keV
.
The
β
-delayed
γ
spectroscopy of
81
As has been performed using a purified beam of
81
Ge
(
9
/
2
+
)
ground state at the Ion Guide Isotope Separator On-Line facility (IGISOL). The
81
Ge
+
ions were ...produced using proton-induced fission of
232
Th and selected with the double Penning trap JYFLTRAP for the post-trap decay spectroscopy measurements. The low-spin
(
1
/
2
+
)
isomeric-state ions
81
m
Ge
+
were not observed in the fission products. The intrinsic half-life of the
81
Ge ground state has been determined as
T
1
/
2
=
6.4
(
2
)
s
, which is significantly shorter than the literature value. A new level scheme of
81
As has been built and is compared to shell-model calculations.
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