Application of the EXtrapolated Efficiency Method (EXEM) to infer the gamma-cascade detection efficiency in the actinide region

The study of transfer-induced gamma-decay probabilities is very useful for understanding the surrogate-reaction method and, more generally, for constraining statistical-model calculations. One of the main difficulties in the measurement of gamma-decay probabilities is the determination of the gamma-cascade detection efficiency. In [Nucl. Instrum. Meth. A 700, 59 (2013)] we developed the Extrapolated Efficiency Method (EXEM), a new method to measure this quantity. In this work, we have applied, for the first time, the EXEM to infer the gamma-cascade detection efficiency in the actinide region. In particular, we have considered the 238U(d,p)239U and 238U(3He,d)239Np reactions. We have performed Hauser-Feshbach calculations to interpret our results and to verify the hypothesis on which the EXEM is based. The determination of fission and gamma-decay probabilities of 239Np below the neutron separation energy allowed us to validate the EXEM

LITERARY PORTRAIT AS ONE OF THE MEANS TO CHARACTERIZE A PERSONAGE (ON THE MATERIAL OF THE SHORT STORY BY W.S. MAUGHAM «RED»)

Литературный портрет характерологичен. По внешним чертам мы можем судить о характере персонажа. При этом портрет может быть снабжен авторским комментарием, раскрывающим связи портрета и характера, а может действовать сам по себе. В этом случае автор полагается на читателя, что выводы о характере персонажа он сделает сам. Такой портрет требует более пристального внимания.The literary portrait is one of the means of characterization. Judging by the outward features we can evaluate the personage’s character. The portrait may be supplied by the author’s comments which reveal the connections between the portrait and the character, but also it can be implicit. In this case the author relies on the reader and his skills to decode the personage’s character. This type of portrait requires more attention to it

First observation of low-lying excited states in the very neutron-rich 95Kr^{95}Kr

Microsecond isomers of neutron-rich nuclei in the mass A=95 chain were investigated at the ILL reactor, Grenoble. These nuclei were produced by thermal-neutron induced fission of $^{241}Pu$. The detection is based on time correlation between fission fragments selected by the Lohengrin mass spectrometer and the $\gamma$-rays from the isomers. In this paper the decay scheme of an isomer of half life 1.4(2) micro second in $^{95}Kr$ is reported. It is the first time that excited states of this nucleus have been measured. These data show that this neutron rich N = 59 isotone is spherical at low excitation energy

Shape coexistence in the very neutron-rich odd-odd 96Rb^{96}Rb

Microsecond isomers of neutron-rich nuclei in the masses A=96 and 98 were reinvestigated at the ILL reactor (Grenoble). These nuclei were produced by thermal-neutron induced fission of $^{241}$Pu. The detection is based on time correlation between fission fragments selected by the Lohengrin mass spectrometer, and the $\gamma$ rays and conversion electrons from the isomers. A new level scheme of $^{96}$Rb is proposed. We have found that the ground state and low-lying levels of this nucleus are rather spherical, while a rotational band develops at 461 keV energy. This bans has properties consistent with a $\pi[431 3/2] x \nu[541 3/2]K = 3^-$ Nilsson assignment and a deformation $\beta_2 > 0.28$. It is fed by a $10^-$ microsecond isomer consistent with a $\pi(g_{9/2})\nu(h_{11/2})$ sperical configuration. It is interesting to note that the same unique-parity states $\pi(g_{9/2})$ and $\nu(h_{11/2})$ are present in the same nucleus in a deformed and in a spherical configuration. The neighbouring odd-odd nucleus $^{98}$Y presents a strong analogy with $^{96}$Rb and is also discussed

Left ventricular diastolic dysfunction and transmitral blood flow parameters in patients after COVID-19

Background. People who previously had COVID-19 infection have an increased risk of developing cardiovascular diseases. Left ventricular diastolic dysfunction is an early marker of the development of cardiac pathology. Its early detection is important for the adequate therapy order and dynamic monitoring of patients. In this regard, it seems relevant to study the effect of a recent COVID-19 infection on the left ventricular diastolic function and transmitral blood flow parameters in apparently healthy individuals without clinical and instrumental signs of cardiovascular pathology. The aim of the study. To assess the changes in the diastolic and systolic function of  the left ventricle, its anatomical parameters and transmitral blood flow parameters in two groups of  apparently healthy individuals: those who had and those who had not COVID-19 infection. Materials and methods. Transthoracic echocardiography was performed according to the standard technique and its results were analyzed in 66 examined patients who were recognized as apparently healthy according to the results of  regular comprehensive clinical and instrumental studies. The first group included 30 individuals who underwent an echocardiographic study before or during the COVID-19 pandemic, but did not have a coronavirus infection; the second group consisted of 36 people who recovered from COVID-19. The indicators of the presence of left ventricular diastolic dysfunction and the transmitral blood flow parameters were assessed. The study was approved at a meeting of the Medical Ethics Committee under the Ministry of Health of the Republic of Karelia and of Petrozavodsk State University (Minutes No. 47 of 01.11.2023). Results. The frequency of the left ventricular diastolic dysfunction did not differ in  the  first and second groups of patients. Statistically significant differences were recorded in the average flow deceleration time for both early and late filling of the left ventricle in people who had and did not have COVID-19 infection. A change in the phase structure of the transmitral blood flow may be an early manifestation of intracardiac hemodynamic disorders in people who have recovered from COVID-19

Role of Multichance Fission in the Description of Fission-Fragment Mass Distributions at High Energies

Fission-fragment mass distributions were measured for U237-240, Np239-242, and Pu241-244 populated in the excitation-energy range from 10 to 60 MeV by multinucleon transfer channels in the reaction O18+U238 at the Japan Atomic Energy Agency tandem facility. Among them, the data for U240 and Np240,241,242 were observed for the first time. It was found that the mass distributions for all the studied nuclides maintain a double-humped shape up to the highest measured energy in contrast to expectations of predominantly symmetric fission due to the washing out of nuclear shell effects. From a comparison with the dynamical calculation based on the fluctuation-dissipation model, this behavior of the mass distributions was unambiguously attributed to the effect of multichance fission

Measurement of fission-fragment mass distributions in the multinucleon transfer channels of the 18O+237Np^18O+^237Np reaction

International audienceFission-fragment mass distributions for 23 nuclei (U234−237, Np236−239, Pu238−241, Am240−243, Cm242−245, and Bk244−246) were measured using the multinucleon transfer approach in the reaction of O18+Np237, and their excitation-energy dependence was obtained up to a maximum of 70 MeV. Among them, the low-energy fission of Np236, Pu238, and Cm245 is reported for the first time. The experimental data for all the studied nuclei were compared to the Langevin calculations. The calculation which takes into account the effects of multichance fission well reproduced the peak-to-valley ratio and mass-asymmetric peak positions of the distributions. The angular momentum given to the fissioning nucleus is also discussed

Fission fragments mass distributions of nuclei populated by the multinucleon transfer channels of the 18O + 232Th reaction

It is shown that the multinucleon transfer reactions is a powerful tool to study fission of exotic neutron-rich actinide nuclei, which cannot be accessed by particle-capture or heavy-ion fusion reactions. In this work, multinucleon transfer channels of the 18O +  232Th reaction are used to study fission of fourteen nuclei 231,232,233,234Th, 232,233,234,235,236Pa, and 234,235,236,237,238U. Identification of fissioning nuclei and of their excitation energy is performed on an event-by-event basis, through the measurement of outgoing ejectile particle in coincidence with fission fragments. Fission fragment mass distributions are measured for each transfer channel, in selected bins of excitation energy. In particular, the mass distributions of 231,234Th and 234,235,236Pa are measured for the first time. Predominantly asymmetric fission is observed at low excitation energies for all studied cases, with a gradual increase of the symmetric mode towards higher excitation energy. The experimental distributions are found to be in general agreement with predictions of the fluctuation–dissipation model