Angular Distribution of the Scission Neutrons with Respect to the Fission Axis

AbstractWe study the angular distribution of the scission neutrons in a time dependent approach. This implies the numerical solution of the bi-dimensional time-dependent Schrödinger equation (TDSE) with time-dependent potential. To describe the axially symmetric extremely deformed nuclear shapes involved, we have used modified Cassini ovals. The Hamiltonian in cylindrical coordinates is discretized on a bi-dimensional grid, using finite difference approximations of the derivatives. The initial wave-functions for TDSE are the eigensolutions of the stationary Schrödinger equation whose potential corresponds to the pre-scission point (when the neck connecting the primary fission fragments starts to break). The time evolution is calculated by a Crank-Nicolson scheme until the neck dissappears (the post-scission point). The resulting wave-functions are then propagated keeping the last configuration to further intervals of time. We investigate the nucleus 236U at different mass asymmetries. The numerical solutions can be used to evaluate relevant physical quantities. Among them, the current density, a key quantity in the angular distribution calculation. The angular distribution of the scission neutrons is a priori a way to separate them from other neutron components. Moreover our preliminary results show a striking similarity with the angular distribution of the neutrons evaporated from fully accelerates fragments

Design of a novel TiO2/airgap-based polarizing micro beam splitter cube

Polarizing beam splitters are key elements widely used in different optical instruments. This paper introduces the design and simulation of a novel thin-film multilayer polarizing micro beam splitter based on airgap layers (n = 1.002828 at 400 nm). The negligible absorption coefficient of the air over a wide spectral region (κ ≈ 0 from about 200 nm and higher) satisfies the conditions of a perfect low refractive index material (L). Moreover, using titanium dioxide (TiO2) as high refractive index material (H), a very high refractive index contrast is obtained. The micro beam splitter optical structure consists in a 7 optimized multilayer of TiO2 and air, providing a refractive contrast higher than 1.2. The polarizing beam splitter cube is projected in a borosilicate glass substrate (BK7) and the optical multilayer obtained, expressed in multiples of the quarter wavelength optical thickness – QWOT, is 1.6H L 1.1H 1.5L 1.1H L 1.6H. This optical structure ensures the transmission of p- polarization and the reflection of s- polarization, from visible to NIR spectral range, over a bandwidth higher than 170 nm. Additionally, the designed polarizing beam splitter can be fabricated using standard microtechnology fabrication processes.This work is supported by ANI through the Brain-Lighting project by FEDER funds through Portugal 2020, COMPETE 2020 with the reference POCI-01-0247-FEDER-003416

Time-dependent formalism for the decay of ground-state deformed nuclei by proton emission : a numerical challenge /.

The numerical challenge associated with the time-dependent approach to the general problem of bi-dimensional quantum - tunneling is discussed and methods towards its application to concrete problems are developed

Adult quality of life in congenital hydrocephalus operated cases: A twenty years retrospective study

Congenital hydrocephalus is a health problem in many countries and in Romania the pediatric neurosurgical department of the Emergency Hospital “Bagdasar-Arseni” has a large number of such patients. This is a retrospective study and it includes the patients with congenital hydrocephalus operated between 1992 and 2012 in the pediatric neurosurgical department of the Emergency Hospital “Bagdasar-Arseni”. The functional outcome was assessed using Karnofsky Performance Scale, Hydrocephalus Outcome Questionnaire and Glasgow outcome scale. The total number of the patients was 372, with a predominance of boys (212 boys versus 160 girls) and at the time of our study 168 patients were over 16 years old. Functional outcome of the children over 16 years old assessed using Karnofsky Performance Scale, showed that 73 patients were above 80 and leading independent lives, and 95 were less than 80 points. The results would be better if all these patients would benefit from schooling for children with special needs

New technics for removal of intradural spinal tumours

Introduction. Neuronavigation is a computer-assisted technology based on pre- and intraoperative images that permit neurosurgeons to have a better approach of the brain and intradural spinal tumors. The neuronavigation systems have been a significant progress in neurosurgery. These systems allow neurosurgeons to evaluate surgical risks, select the best interventional method, localize better the tumors in order to improve the accuracy of the resection and decide on the optimal trajectory for the surgical procedure, resulting in decreased patient morbidity and mortality. Material: Spinal cord tumors are rare and uncommon lesions. Their growth result in compression of the spinal cord, which can cause severe neurologic deficits such as limb dysfunction, motor and sensation loss with the possibility of leading to death. We present o short report of a study publicated by Stefini et al. in 2018 regarding the use of neuronavigation for removal of intradural spinal tumors. Conclusion: The benefits of using neuronavigation in resection of the intradural spinal tumors include decreased risk of bad localization of the tumor, minimal invasive surgery technique and reduction of bone removal