M. Ramdhane

Université Grenoble Alpes, Physics, Faculty Member

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$Research paper thumbnail of Laser ionization in $\beta$-decay studies of Zn and Mn nuclei$

Laser ionization in $\beta$-decay studies of Zn and Mn nuclei

A la recherche des noyaux dans les états extrêmes

First observation of neutron single particle states in 133Sn

$Research paper thumbnail of Experimental investigation of N= Z nuclei around A $\\ simeq $80 through radioactive decay$

Experimental investigation of N= Z nuclei around A $\\ simeq $80 through radioactive decay

Laser ionization in b-decay studies of Zn and Mn nuclei

Natural radioelement concentrations in fertilizers and the soil of the Mila region of Algeria

Journal of Radiation Research and Applied Sciences, 2017

The addition of inorganic fertilizers to treat crop soil and increase its production has become a... more The addition of inorganic fertilizers to treat crop soil and increase its production has become a necessity and a tool used around the world. These fertilizers contain different quantities of uranium and thorium. Therefore, tons of radionuclides from natural radioactive series 238 U, 235 U and 232 Th are dispersed in the environment due to a high use of fertilizer in agriculture. In this work, the radioactivity levels were determined in two fertilizers and in fertilized and unfertilized soil samples collected at various depths from the Algerian agricultural region of El-Athmania Mila, using high resolution gamma ray spectroscopy. The activity concentrations of 226 Ra, 232 Th and 40 K for fertilized and unfertilized soil samples were found unchanged as a function of depth and ranged from 23.72

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Gamow-Teller beta decay of 29–31Na comparison with shell-model estimates

AIP Conference Proceedings, 1987

Gamma rays and delayed‐neutron processes subsequent to beta decay of the neutron‐rich 29–31Na iso... more Gamma rays and delayed‐neutron processes subsequent to beta decay of the neutron‐rich 29–31Na isotopes are studied in singles an coincidence mode with mass‐separated sources at ISOLDE. Improved level schemes are presented for mass 29 and 30, whose features substantially agree with shell‐model predictions. The deduced Gamow‐Teller strengths are discussed as well as the occurrence of negative parity intruder states in the daughter nuclei.

$Research paper thumbnail of The $^{34,35}$AI $\beta$ decay to $^{34,35}$Si$

The $^{34,35}$AI $\beta$ decay to $^{34,35}$Si

Gamow-Teller beta decay ofNa29and comparison with shell-model predictions

Physical Review C, 1987

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Beta decay and structure of exotic nuclei in the mass regions N=Z, A ~ 70 and near the N=20 closed shell

Brazilian Journal of Physics, 2004

This paper describes two beta decay experiments performed at the CERN/ISOLDE mass separator. The ... more This paper describes two beta decay experiments performed at the CERN/ISOLDE mass separator. The structure of 74 Kr has been studied using a total absorption γ spectrometer (TAgS). The measured Gamow-Teller strength is presented and compared to HFBCS+QRPA calculations. The 33 Na decay is also presented. The structure of the 33 Mg daughter nucleus is compared to shell-model calculations, showing for the first time an inversion of states in the A 35 mass region.

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Identification of the(9/2+to(5/2−transition inSe69

Physical Review C, 1988

Gamma rays from Se have been investigated using the reaction Ca(' S,2pn y) Se between 80 and 110 ... more Gamma rays from Se have been investigated using the reaction Ca(' S,2pn y) Se between 80 and 110 MeV beam energy. Isotopic identification was based on excitation functions, n-y and ny-y coincidences, as well as genetic relationships. An isomeric state (Ti/2-853+78 ns) was found at 575.0+0.4 keV decaying to the first excited state which was located at 40.2+0.3 keV. The isomeric state lifetime reveals the same degree of inhibition as in analogous M2 (-+~z) transitions and the excitation energy displays the systematic trend of the first 2 + state in the N = 35 and N =37 isotones. The observed y decay properties are consistent with J =-, ' for the Se ground state, in agreement with the indications given by previous beta decay studies. A first level scheme, including four levels in Se, is proposed.

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Characterization of Diamond and Silicon Carbide Detectors With Fission Fragments

Frontiers in Physics, 2021

Experimental fission studies for reaction physics or nuclear spectroscopy can profit from fast, e... more Experimental fission studies for reaction physics or nuclear spectroscopy can profit from fast, efficient, and radiation-resistant fission fragment (FF) detectors. When such experiments are performed in-beam in intense thermal neutron beams, additional constraints arise in terms of target-detector interface, beam-induced background, etc. Therefore, wide gap semi-conductor detectors were tested with the aim of developing innovative instrumentation for such applications. The detector characterization was performed with mass- and energy-separated fission fragment beams at the ILL (Institut Laue Langevin) LOHENGRIN spectrometer. Two single crystal diamonds, three polycrystalline and one diamond-on-iridium as well as a silicon carbide detector were characterized as solid state ionization chamber for FF detection. Timing measurements were performed with a 500-µm thick single crystal diamond detector read out by a broadband amplifier. A timing resolution of ∼10.2 ps RMS was obtained for FF...

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New nuclear structure data after fission: The g.s. of 136Sb

EPJ Web of Conferences, 2018

Nuclei in the neutron-rich region beyond 132 Sn have been produced recently by various experiment... more Nuclei in the neutron-rich region beyond 132 Sn have been produced recently by various experiments using fission. Using isomer and -decay studies nuclear structure data has been collected on the orbital evolution and collectivity in the region with both the increase of proton and neutron numbers. Examples on particular questions related to the g.s. of the A=136 odd-odd 136 Sb nucleus and its heavier neighbours are given in the scope of expectations by shell-model theory.

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New β -decay spectroscopy of the Te137 nucleus

Physical Review C

Background: Nuclear spectroscopy of neutron-rich isotopes provides important information on their... more Background: Nuclear spectroscopy of neutron-rich isotopes provides important information on their nuclear structure and has a valuable impact on the modeling of the r-process path. Particularly interesting are nuclei close to doubly-magic species, e.g., 132 Sn, with only several valence particles. Such is the barely explored 137 I nucleus, investigated here in detail. Purpose: To establish excited states in 137 I, β decay of the 137 Te ground state is studied. In addition, the unknown β-delayed neutron-emission channel of 137 Te to 136 I is inspected. Search for levels and for candidates for Gamow-Teller and first-forbidden transitions between the mother nucleus and excited states in the daughter nucleus is conducted within the experimental observations. Methods: β-delayed γ-ray spectroscopy is employed to study excited states in 137 I. The nucleus is populated in the decay of a mass-separated beam of 137 Te, produced in neutron-induced fission of 235 U. Results: The new level scheme of 137 I populated in β decay is established. The half-life T 1/2 of 137 Te is determined to be 2.46(5) s. The β-delayed neutron-emission probability P n value of 137 Te is deduced as a lower limit to be 2.63(85)%. Conclusions: The experimental results are an important input to the theoretical description of nuclei in the region, being well interpreted within large-scale shell model calculations, and provide essential information on the first-forbidden transitions beyond N = 82 and Z = 50.

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Structure of high-lying levels populated in the ⁹⁶Y → ⁹⁶Zr β decay

The nature of Jπ=1− levels of 96Zr below the β-decay Qβ value of 96Y has been investigated in hig... more The nature of Jπ=1− levels of 96Zr below the β-decay Qβ value of 96Y has been investigated in high-resolution γ-ray spectroscopy following the β decay as well as in a campaign of inelastic photon scattering experiments. Branching ratios extracted from β decay allow the absolute E1 excitation strength to be determined for levels populated in both reactions. The combined data represents a comprehensive approach to the wavefunction of 1− levels below the Qβ value, which are investigated in the theoretical approach of the Quasiparticle Phonon Model. This study clarifies the nuclear structure properties associated with the enhanced population of high-lying levels in the 96Ygs β decay, one of the three most important contributors to the high-energy reactor antineutrino spectrum

$Research paper thumbnail of Structure of $^{83}$As, $^{85}$As and $^{87}$As: from semi-magicity to $\gamma$-softness$

Structure of $^{83}$As, $^{85}$As and $^{87}$As: from semi-magicity to $\gamma$-softness

The structure of $^{83}$As, $^{85}$As and $^{87}$As have been studied in fusion-fission reaction ... more The structure of $^{83}$As, $^{85}$As and $^{87}$As have been studied in fusion-fission reaction $^{238}$U+$^9$Be. Fission fragments were identified in mass and atomic number using the VAMOS++ spectrometer and the coincident $\gamma$-rays were detected in the $\gamma$-ray tracking array AGATA. New transitions in $^{83}$As and $^{85}$As are reported and placed in the level schemes. A level scheme of the excited states in $^{87}$As is proposed for the first time. The data are interpreted in frame of Large-Scale Shell-Model calculations, SU3 symmetries and Beyond Mean-Field frameworks. A spherical regime at magic number $N$=50 is predicted and the location of the proton $g_{9/2}$ orbital is proposed for the first time. Development of collectivity in a prolate deformed, $\gamma$-soft regime in the open shell cases $^{85}$As and $^{87}$As, most neutron-rich isotopes beyond $N$=50, is concluded. Data and theoretical calculations give confidence to a relatively high extrapolated excitation energy about 4 MeV of the $9/2^+$ state in $^{79}$Cu, one proton above $^{78}$Ni.

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$Research paper thumbnail of Structure of high-lying levels populated in the $^{96}$Y $\rightarrow ^{96}$Zr $\beta$ decay$

Structure of high-lying levels populated in the $^{96}$Y $\rightarrow ^{96}$Zr $\beta$ decay

arXiv: Nuclear Experiment, 2020

The nature of $J^{\pi}=1^-$ levels of $^{96}$Zr below the $\beta$-decay $Q_{\beta}$ value of $^{9... more The nature of $J^{\pi}=1^-$ levels of $^{96}$Zr below the $\beta$-decay $Q_{\beta}$ value of $^{96}$Y has been investigated in high-resolution $\gamma$-ray spectroscopy following the $\beta$ decay as well as in a campaign of inelastic photon scattering experiments. Branching ratios extracted from $\beta$ decay allow the absolute $E1$ excitation strength to be determined for levels populated in both reactions. The combined data represents a comprehensive approach to the wavefunction of $1^-$ levels below the $Q_{\beta}$ value, which are investigated in the theoretical approach of the Quasiparticle Phonon Model. This study clarifies the nuclear structure properties associated with the enhanced population of high-lying levels in the $^{96}$Y$_{gs}$ $\beta$ decay, one of the three most important contributors to the high-energy reactor antineutrino spectrum.

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New Neutron Rich Nuclei Near {sup 208}Pb

The level properties near the stable doubly-magic nuclei formed the experimental grounds for the ... more The level properties near the stable doubly-magic nuclei formed the experimental grounds for the theoretical description of nuclear structure. However with a departure from the beta-stability line, the classical well-established shell structure might be modified. In particular, it may even vanish for extremely exotic neutron-rich nuclei near the neutron-drip line. Presently, it is impossible to verify such predictions by a direct experimental studies of these exotic objects. However, one may try to observe and understand the evolution of the nuclear structure while departing in the experiment as far as possible from the stable nuclei. An extension of experimental nuclear structure studies towards the nuclei characterized by high neutron excess is crucial for such verifications as well as for the {tau}-process nucleosynthesis scenario. Heavy neutron-rich nuclei, south-east of doubly-magic {sup 208}Pb, were always very difficult to produce and investigate. The nuclei like {sup 218}Po ...

Natural radioelement concentrations in the soil of the Mila region of Algeria

EPJ Web of Conferences, 2017

In this study, the levels of the natural and artificial radioactivity in soil samples collected a... more In this study, the levels of the natural and artificial radioactivity in soil samples collected at various depths from Algerian agricultural region El-Athmania Mila was measured. Activity concentrations of the concerned radionuclides were determined by gamma-ray spectrometry using a high-purity germanium detector. The activity concentrations of 226 Ra, 232 Th and 40 K were found unchanged as a function of depth and ranged from 23.72±2.37to 65.47±5.06 Bq.kg -1 for 226 Ra, from 26.45±0.78 to 27.10±0.80 Bq.kg -1 for 232 Th and from 220.80±10.01 to 260.70±8.24 Bq.kg -1 for 40 K respectively. To evaluate the radiological hazard of radioactivity in samples, the radium equivalent activity (Raeq), the absorbed dose rate (D), the annual effective dose and the external (Hex) and internal hazard indices (Hin) were calculated. The mean of the excess lifetime cancer risk observed in this study are under the world's mean values.

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$Research paper thumbnail of Study of Intermediate-spin States of $^{98}$Y$

Study of Intermediate-spin States of $^{98}$Y

Acta Physica Polonica B, 2016

The nuclear structure of the odd-odd nucleus 98 Y has been re-investigated by observing prompt γ ... more The nuclear structure of the odd-odd nucleus 98 Y has been re-investigated by observing prompt γ rays emitted following the proton-induced fission of a 238 U target, using the JUROGAM-II multidetector array. New highspin decays have been observed and placed in the level schemes using triple coincidences. The experimental level energies and γ-decay patterns are compared to GICM and QPRM calculations, assuming that this neutronrich N = 59 isotone is spherical at low energies and prolate deformed at intermediate spins.

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M. Ramdhane

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