Statistical (n, γ ) cross section model comparison for short-lived nuclei.

Neutron-capture cross sections of neutron-rich nuclei are calculated using a Hauser-Feshbach model when direct experimental cross sections cannot be obtained. A number of codes to perform these calculations exist, and each makes different assumptions about the underlying nuclear physics. We investigated the systematic uncertainty associated with the choice of Hauser-Feshbach code used to calculate the neutron-capture cross section of a short-lived nucleus. The neutron-capture cross section for 73 Zn (n, γ ) 74 Zn was calculated using three Hauser-Feshbach statistical model codes: TALYS, CoH, and EMPIRE. The calculation was first performed without any changes to the default settings in each code. Then an experimentally obtained nuclear level density (NLD) and γ -ray strength function ( γ SF ) were included. Finally, the nuclear structure information was made consistent across the codes. The neutron-capture cross sections obtained from the three codes are in good agreement after including the experimentally obtained NLD and γ SF , accounting for differences in the underlying nuclear reaction models, and enforcing consistent approximations for unknown nuclear data. It is possible to use consistent inputs and nuclear physics to reduce the differences in the calculated neutron-capture cross section from different Hauser-Feshbach codes. However, ensuring the treatment of the input of experimental data and other nuclear physics are similar across multiple codes requires a careful investigation. For this reason, more complete documentation of the inputs and physics chosen is important. Supplementary Information: The online version contains supplementary material available at 10.1140/epja/s10050-023-00920-0.

Publisher's Note: Experimental Neutron Capture Rate Constraint Far from Stability [Phys. Rev. Lett. 116, 242502 (2016)].

This corrects the article DOI: 10.1103/PhysRevLett.116.242502.

Strong Neutron-γ Competition above the Neutron Threshold in the Decay of

The ß-decay intensity of ^{70}Co was measured for the first time using the technique of total absorption spectroscopy. The large ß-decay Q value [12.3(3) MeV] offers a rare opportunity to study ß-decay properties in a broad energy range. Two surprising features were observed in the experimental results, namely, the large fragmentation of the ß intensity at high energies, as well as the strong competition between γ rays and neutrons, up to more than 2 MeV above the neutron-separation energy. The data are compared to two theoretical calculations: the shell model and the quasiparticle random phase approximation (QRPA). Both models seem to be missing a significant strength at high excitation energies. Possible interpretations of this discrepancy are discussed. The shell model is used for a detailed nuclear structure interpretation and helps to explain the observed γ-neutron competition. The comparison to the QRPA calculations is done as a means to test a model that provides global ß-decay properties for astrophysical calculations. Our work demonstrates the importance of performing detailed comparisons to experimental results, beyond the simple half-life comparisons. A realistic and robust description of the ß-decay intensity is crucial for our understanding of nuclear structure as well as of r-process nucleosynthesis.

Experimental Neutron Capture Rate Constraint Far from Stability.

Nuclear reactions where an exotic nucleus captures a neutron are critical for a wide variety of applications, from energy production and national security, to astrophysical processes, and nucleosynthesis. Neutron capture rates are well constrained near stable isotopes where experimental data are available; however, moving far from the valley of stability, uncertainties grow by orders of magnitude. This is due to the complete lack of experimental constraints, as the direct measurement of a neutron-capture reaction on a short-lived nucleus is extremely challenging. Here, we report on the first experimental extraction of a neutron capture reaction rate on ^{69}Ni, a nucleus that is five neutrons away from the last stable isotope of Ni. The implications of this measurement on nucleosynthesis around mass 70 are discussed, and the impact of similar future measurements on the understanding of the origin of the heavy elements in the cosmos is presented.

Evidence for partial dynamical symmetries in atomic nuclei.

Symmetries in nature offer very simple descriptions of complex systems. Partial Dynamical Symmetries (PDS) can considerably broaden their relevance. To present the first extensive test of a PDS for nuclei, we compare an SU(3) PDS to gamma to ground band B(E2) values for 47 deformed nuclei. The parameter-free PDS is found to be quite successful, but with characteristic discrepancies, suggesting that symmetry remnants are more pervasive than heretofore realized. Furthermore, the SU(3) PDS gives new insights into collective models (e.g., interacting boson approximation). If these reproduce the PDS, they reflect finite size effects, while differences from the PDS point to SU(3) configuration mixing.

Prenatal abnormal features of the fourth ventricle in Joubert syndrome and related disorders.

Joubert syndrome and related disorders (JSRD) are characterized by absence or underdevelopment of the cerebellar vermis and a malformed brainstem. This family of disorders is a member of an emerging class of diseases called ciliopathies. We describe the abnormal features of the brain, particularly the fourth ventricle, in seven fetuses affected by JSRD. In three cases abnormality of the fourth ventricle was isolated and in four cases there were associated malformations. The molar tooth sign (MTS) was always present and visible on two-dimensional ultrasound and, when performed, on three-dimensional ultrasound and magnetic resonance imaging. The fourth ventricle was always abnormal, in both axial and sagittal views, presenting pathognomonic deformities. It is important to identify JSRD, preferably prenatally or at least postnatally, due to its high risk of recurrence of about 25%. A detailed prenatal assessment of the fourth ventricle in several views may help to achieve this goal.

New precision measurements of the 235U(n,γ) cross section.

The neutron capture cross section of (235)U was measured for the neutron incident energy region between 4 eV and 1 MeV at the DANCE facility at the Los Alamos Neutron Science Center with an unprecedented accuracy of 2-3% at 1 keV. The new methodology combined three independent measurements. In the main experiment, a thick actinide sample was used to determine neutron capture and neutron-induced fission rates simultaneously. In the second measurement, a fission tagging detector was used with a thin actinide sample and detailed characteristics of the prompt-fission gamma rays were obtained. In the third measurement, the neutron scattering background was characterized using a sample of (208)Pb. The relative capture cross section was obtained from the experiment with the thick (235)U sample using a ratio method after the subtraction of the fission and neutron scattering backgrounds. Our result indicates errors that are as large as 30% in the 0.5-2.5 keV region, in the current knowledge of neutron capture as embodied in major nuclear data evaluations. Future modifications of these databases using the improved precision data given herein will have significant impacts in neutronics calculations for a variety of nuclear technologies.

Proton-induced cross sections relevant to production of 225Ac and 223Ra in natural thorium targets below 200 MeV.

Cross sections for (223,)(225)Ra, (225)Ac and (227)Th production by the proton bombardment of natural thorium targets were measured at proton energies below 200 MeV. Our measurements are in good agreement with previously published data and offer a complete excitation function for (223,)(225)Ra in the energy range above 90 MeV. Comparison of theoretical predictions with the experimental data shows reasonable-to-good agreement. Results indicate that accelerator-based production of (225)Ac and (223)Ra below 200 MeV is a viable production method.

225Ac and 223Ra production via 800 MeV proton irradiation of natural thorium targets.

Cross sections for the formation of (225,227)Ac, (223,225)Ra, and (227)Th via the proton bombardment of natural thorium targets were measured at a nominal proton energy of 800 MeV. No earlier experimental cross section data for the production of (223,225)Ra, (227)Ac and (227)Th by this method were found in the literature. A comparison of theoretical predictions with the experimental data shows agreement within a factor of two. Results indicate that accelerator-based production of (225)Ac and (223)Ra is a viable production method.

The influence of primary health care organizational models on patients' experience of care in different chronic disease situations.

OBJECTIVES: To examine the extent to which experience of care varies across chronic diseases, and to analyze the relationship of primary health care (PHC) organizational models with the experience of care reported by patients in different chronic disease situations. METHODS: We linked a population survey and a PHC organizational survey conducted in two regions of Quebec. We identified five groups of chronic diseases and contrasted these with a no-chronic-disease group. RESULTS: Accessibility of care is low for all chronic conditions and shows little variation across diseases. The contact and the coordination-integrated models are the most accessible, whereas the single-provider model is the least. Process and outcome indices of care experience are much higher than accessibility for all conditions and vary across diseases, with the highest being for cardiovascular-risk-factors and the lowest for respiratory diseases (for people aged 44 and under). However, as we move from risk factors to more severe chronic conditions, the coordination-integrated and community models are more likely to generate better process of care, highlighting the greater potential of these two models to meet the needs of more severely chronically ill individuals within the Canadian health care system.

Prenatal management of congenital infantile fibrosarcoma: unexpected outcome.

We report the case of a large leg tumor in a fetus at 36 weeks of gestation. The tumor's location, ultrasound characteristics and magnetic resonance imaging (MRI) findings enabled a prenatal diagnosis of congenital fibrosarcoma and allowed us to establish the prognosis. After multidisciplinary discussion, it was decided that the pregnancy should continue to 38 weeks, with surgery or neo-adjuvant chemotherapy scheduled after delivery. Unfortunately, the tumor unexpectedly burst in utero and the newborn died of the consequences of hemorrhagic shock, despite rapid amputation. Histological examination confirmed the nature of the tumor. The prognosis of congenital fibrosarcoma is generally good when there are no metastases. MRI is key to establishing a prenatal diagnosis. However, rupture of the tumor can result in fatal hemorrhaging and the pregnancy should be monitored closely before scheduled delivery.

[Ultrasound of the neonatal hip: initial evaluation and follow-up]. / Échographie de la hanche néonatale : bilan initial et suivi thérapeutique.

Developmental dysplasia of the hip can arise in utero due to a dislocating posture, sometimes associated with predisposing genetic factors. The ideal time for diagnosis is during the neonatal period and adequate screening procedures must be in place. Indeed, the plasticity of hyaline cartilage and fibrocartilage combined with the growth potential at this age nearly always result in rapid complete resolution of the deformity. Ultrasound, when indicated, is the best imaging modality for diagnostic confirmation. It allows evaluation of the osteocartilaginous structures, joint space and soft tissues. Ultrasound provides the clinician with a reliable morphologic and dynamic evaluation tool improving the diagnostic accuracy and guiding orthopedic treatment. Our experience, dating back to 1985, is based on a population imaged between 2007 and 2009. From a total of 2480 neonates screened because of abnormal finding or risk factors, we identified 257 cases of dislocation (10%) in 191 neonates : 14 cases of nonreducible dislocation (10 neonates), 30 cases of reducible hip dislocation (24 neonates), 97 cases of dislocatable hip (73 neonates) and 116 cases of subluxable hip (84 neonates). Clinical and sonographic follow-up demonstrated therapeutic success in 237 cases (93%) and failure in 20 cases (one case of subluxable hip, two cases of dislocatable hip, three cases of dislocated hip, 14 cases of nonreducible hip dislocation). Imaging follow-up (6 to 24 months) showed asymmetry in the size of the proximal femoral epiphyses in 20 cases (with resolution in 10 cases), three cases of dysplasia and one case of post-reduction osteochondritis.

Neutron cross-sections for next generation reactors: new data from n_TOF.

In 2002, an innovative neutron time-of-flight facility started operation at CERN: n_TOF. The main characteristics that make the new facility unique are the high instantaneous neutron flux, high resolution and wide energy range. Combined with state-of-the-art detectors and data acquisition system, these features have allowed to collect high accuracy neutron cross-section data on a variety of isotopes, many of which radioactive, of interest for Nuclear Astrophysics and for applications to advanced reactor technologies. A review of the most important results on capture and fission reactions obtained so far at n_TOF is presented, together with plans for new measurements related to nuclear industry.

Voiding ultrasonography: evaluation of the detection of vesicoureteral reflux based on the review of digital ultrasound clips.

PURPOSE: To evaluate the accuracy of voiding urosonography (VUS) compared to X-ray voiding cystoureterography (VCUG) for the detection and grading of vesicoureteral reflux (VUR) by standardised reading of digital clips obtained from VUS and digital images from VCUG. MATERIALS AND METHODS: Approval by the ethics committee was obtained, and written, informed consent was given. 130 children (94 girls and 36 boys, mean age of 4.4 years) underwent VUS using Levovist (Schering, Germany) prior to VCUG. Digital VUS clips and digital VCUG images were reviewed by two groups of two radiologists. Results were mainly analysed in terms of reno-ureteral units (RUUs). Intra and interobserver reproducibility was estimated by calculation of kappa coefficient. Calculation of sensitivity and specificity of VUS was made in comparison with VCUG. RESULTS: Intraobserver reproducibility was good to moderate for the detection of VUR using VUS (kappa = 0.67 and 0.53 for each reviewer respectively) and good for the grading of reflux (kappa = 0.64 and 0.70). Interobserver reproducibility was excellent for the detection and grading of VUR using VCUG (kappa = 0.89 and 0.91) but good to moderate for VUS (kappa = 0.73 and 0.51). Compared to VCUG, sensitivity and specificity of VUS for the detection of VUR were 62.7 % and 83.4 %. Concordance for grading was moderate, with a higher grading using VUS. CONCLUSION: Real-time evaluation and diagnosis based on the review of VUS digital clips is achievable. However, there is a need for standardisation of digital records if a second reading by another radiologist or consideration by urologists is needed. Recent advances in US technology and the use of second-generation contrast agents would be promising to improve the feasibility, reproducibility and accuracy of the method.

[Ultrasonography of fetal esophagus: healthy appearance and prenatal diagnosis of a case of esophagus atresia with esotracheal fistula]. / Echographie de l'oesophage foetal: aspect physiologique et application au dépistage anténatal d'une atrésie oesophagienne.

The thoracic part of a fetal esophagus is generally overlooked by usual prenatal ultrasonography. However, screening it might improve the detection rate of esophageal malformations for which prenatal diagnosis remains far from accurate. In this article, we describe the technique which makes it possible to get a precise image of a fetal thoracic esophagus in its more sensitive part: between the trachea and the aorta. After describing the appearance of a healthy thoracic esophagus, we will show how this technique can be used for prenatal detection of esophagus malformations. For this purpose, we provide the case report of a prenatal diagnosis of esophagus atresia with esotracheal fistula.

[MRI of fetal GI tract]. / IRM du tube digestif foetal.

The fetal diagnosis of GI tract abnormalities may be improved by the use of MRI that is able to visualize the normal bowel, may characterize the nature and location of gastrointestinal abnormalities, detect severe malformations, demonstrate the bowel close to cystic or tumoral intra abdominal structures. Our personal experience and recent data of the literature are reported.

Neutron capture cross section measurement of 151Sm at the CERN neutron time of flight facility (n_TOF).

The151Sm(n,gamma)152Sm cross section has been measured at the spallation neutron facility n_TOF at CERN in the energy range from 1 eV to 1 MeV. The new facility combines excellent resolution in neutron time-of-flight, low repetition rates, and an unsurpassed instantaneous luminosity, resulting in rather favorable signal/background ratios. The 151Sm cross section is of importance for characterizing neutron capture nucleosynthesis in asymptotic giant branch stars. At a thermal energy of kT=30 keV the Maxwellian averaged cross section of this unstable isotope (t(1/2)=93 yr) was determined to be 3100+/-160 mb, significantly larger than theoretical predictions.