From RISING to HISPEC/DESPEC

Podolyák, Z

doi:10.1016/j.nimb.2008.05.106

Cited by 25 publications

(7 citation statements)

References 17 publications

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“…The experimental method described here opens new perspectives for lifetime measurements in nuclei far from stability once in-beam γ -ray spectroscopy become possible within the HiSPEC project [60] using RIB beams delivered by the Super-FRS [61] at the future FAIR facility.…”

Section: Discussionmentioning

confidence: 99%

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Lifetime measurement of neutron-rich even-even molybdenum isotopes

Ralet¹,

Piétri²,

Rodríguez³

et al. 2017

Phys. Rev. C

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Background: In the neutron-rich A ≈ 100 mass region, rapid shape changes as a function of nucleon number as well as coexistence of prolate, oblate, and triaxial shapes are predicted by various theoretical models. Lifetime measurements of excited levels in the molybdenum isotopes allow the determination of transitional quadrupole moments, which in turn provides structural information regarding the predicted shape change. Purpose: The present paper reports on the experimental setup, the method that allowed one to measure the lifetimes of excited states in even-even molybdenum isotopes from mass A = 100 up to mass A = 108, and the results that were obtained. Method:The isotopes of interest were populated by secondary knock-out reaction of neutron-rich nuclei separated and identified by the GSI fragment separator at relativistic beam energies and detected by the sensitive PreSPEC-AGATA experimental setup. The latter included the Lund-York-Cologne calorimeter for identification, tracking, and velocity measurement of ejectiles, and AGATA, an array of position sensitive segmented HPGe detectors, used to determine the interaction positions of the γ ray enabling a precise Doppler correction. The lifetimes were determined with a relativistic version of the Doppler-shift-attenuation method using the systematic shift of the energy after Doppler correction of a γ -ray transition with a known energy. This relativistic Doppler-shiftattenuation method allowed the determination of mean lifetimes from 2 to 250 ps. Results: Even-even molybdenum isotopes from mass A = 100 to A = 108 were studied. The decays of the low-lying states in the ground-state band were observed. In particular, two mean lifetimes were measured for the first time: τ = 29.7 Conclusions:The reduced transition strengths B(E2), calculated from lifetimes measured in this experiment, compared to beyond-mean-field calculations, indicate a gradual shape transition in the chain of molybdenum isotopes when going from A = 100 to A = 108 with a maximum reached at N = 64. The transition probabilities decrease for 108 Mo which may be related to its well-pronounced triaxial shape indicated by the calculations.

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Section: Discussionmentioning

confidence: 99%

“…The calibration of the 19 AGATA crystals was performed using 60 Co and 152 Eu sources and followed the standard data-flow treatment of AGATA experiments as described in Refs. [32,33].…”

Section: Fragment Identificationmentioning

confidence: 99%

Lifetime measurement of neutron-rich even-even molybdenum isotopes

Ralet¹,

Piétri²,

Rodríguez³

et al. 2017

Phys. Rev. C

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“…We absolutely need experimental information on the waiting point nuclei. Experiments for the measurement of N = 126 nuclei are progressing, with plans to produce these nuclei in both deep-inelastic [39,40] and fragmentation reactions [41].…”

Section: Resultsmentioning

confidence: 99%

Impact of the first-forbidden β decay on the production of A∼ 195 r-process peak

et al. 2016

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We investigated the effects of first-forbidden transitions in β decays on the production of the r-process A ∼ 195 peak. The theoretical calculated β-decay rates with β-delayed neutron emission were examined using several astrophysical conditions. As the FF decay is dominant in N ∼ 126 neutron-rich nuclei, their inclusion shortens β-decay lifetimes and shifts the abundance peak towards higher masses. Additionally, the inclusion of the β-delayed neutron emission results in a wider abundance peak, and smoothens the mass distribution by removing the odd-even mass staggering. The effects are commonly seen in the results of all adopted astrophysical models. Nevertheless there are quantitative differences, indicating that remaining uncertainty in the determination of half-lives for N = 126 nuclei is still significant in order to determine the production of the r-process peak.

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“…At the Low-Energy Branch (LEB), the main experimental setups are HISPEC/DESPEC (High-resolution In-flight SPECtroscopy/DEcay SPECtroscopy) [6,7], MATS (Precision Measurements of very short-lived nuclei using an Advanced Trapping System for highly-charged ions) and LaSpec (Laser Spectroscopy) [8]. The operation of MATS and LaSpec requires a low-energy beam (up to a few tens of keV) with a small spread in energy and angle.…”

Section: Introductionmentioning

confidence: 99%

Design, construction and cooling system performance of a prototype cryogenic stopping cell for the Super-FRS at FAIR

Ranjan

Dendooven

Purushothaman

et al. 2015

Nuclear Instruments and Methods in Physics Research Section A:

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a b s t r a c tA cryogenic stopping cell for stopping energetic radioactive ions and extracting them as a low energy beam was developed. This first ever cryogenically operated stopping cell serves as prototype device for the Low-Energy Branch of the Super-FRS at FAIR. The cell has a stopping volume that is 1 m long and 25 cm in diameter. Ions are guided by a DC field along the length of the stopping cell and by a combined RF and DC fields provided by an RF carpet at the exit-hole side. The ultra-high purity of the stopping gas required for optimum ion survival is reached by cryogenic operation. The design considerations and construction of the cryogenic stopping cell, as well as some performance characteristics, are described in detail. Special attention is given to the cryogenic aspects in the design and construction of the stopping cell and the cryocooler-based cooling system. The cooling system allows the operation of the stopping cell at any desired temperature between about 70 K and room temperature. The cooling system performance in realistic on-line conditions at the FRS Ion Catcher Facility at GSI is discussed. A temperature of 110 K at which efficient ion survival was observed is obtained after 10 h of cooling. A minimum temperature of the stopping gas of 72 K was reached. The expertise gained from the design, construction and performance of the prototype cryogenic stopping cell has allowed the development of a final version for the Low-Energy Branch of the Super-FRS to proceed.

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From RISING to HISPEC/DESPEC

Cited by 25 publications

References 17 publications

Lifetime measurement of neutron-rich even-even molybdenum isotopes

Lifetime measurement of neutron-rich even-even molybdenum isotopes

Impact of the first-forbidden β decay on the production of A∼ 195 r-process peak

Design, construction and cooling system performance of a prototype cryogenic stopping cell for the Super-FRS at FAIR

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