The 1MW pool-type Portuguese research reactor (RPI) was converted from using highly enriched uranium (HEU) to using low enriched uranium (LEU) fuel in September 2007. Although the new LEU core has the same number of fuel assemblies as the first HEU core, it has three assemblies less than the last HEU core and also has a different arrangement of the beryllium reflectors. Therefore, the primary i...

The assumption that the shape of the epithermal neutron spectrum can be described, in any research reactor, by the 1/E1+α function is a fundamental starting point of the k0 standardization. This assumption may be questioned from a reactor physics viewpoint. The type of moderator, the existence of neutron reflectors, the additional production of (γ, n) neutrons and resonance capture by construct...

Introduction BNCT is an effective method to destroy brain tumoral cells while sparing the healthy tissues. The recommended flux for epithermal neutrons is 10 n/cms, which has the most effectiveness on deep-seated tumors. In this paper, it is indicated that using D-T neutron source and optimizing of Beam Shaping Assembly (BSA) leads to treating brain tumors in a reasonable time where all IAEA re...

A compact and comparatively inexpensive system that is practical for universities is described based on a low-energy, electron storage ring with at least one undulator based oscillator to store photons. If the oscillator cavity length is relativistically corrected to be an harmonic of the ring circumference (LC=βLRn=nB with nB the number of bunches), higher-energy, secondary photons from Compto...

Advanced methods of boron neutron capture therapy (BNCT) use an epithermal neutron beam in conjunction with tumor-targeting boron compounds for irradiation of glioblastomas and metastatic melanomas. A common neutron-producing reaction considered for accelerator-based BNCT is 7Li(p,n)7Be, whose cross section increases very rapidly within several tens of keV of the reaction threshold at 1.88 MeV....

the takmeh-dash region comprises a wide variety of igneous bodies that have been developed from early to late neogen. the granitic rocks and related aplite apophyses have been developed along fault-dominated structures which defines a well pronounced mineralized zone. according to isotopic and fluid inclusion studies, most of the quartz-pyrite units are solution-related with some traces of cu, ...

Detailed simulations of antihydrogen formation have been performed under the conditions of the ATHENA experiment, using several densities of the positron plasma in the range ne = 5 × 1013 m−3 to 1015 m−3. The simulations include only collisional effects, typically resulting in the formation of weakly bound antihydrogen via the three-body process, e+ + e+ + p → H + e+. (Radiative processes, whic...

1293, 2001; [5] Jun I., JPL, pers. comm., 2002; [6] Hahn et al., IEEE Trans. Nuc. Sci., submitted, 2002; [7] Waters, MCNPX Users Manual, LA-UR 02-2607, 2002. Figure 1. Schematic diagram of the NS, rover, and Martian surface model used for this study. Figure 2. Epithermal neutrons (counts per second) versus H2O content for the bottom dry layer. Black and left scale are for the RTG case; red and ...

Epithermal and Fast Neutron Radiography (FNR) are complementary to the conventional radiography with high energy gamma-rays or brems-strahlung radiation and which iarecommonly used for the inspection of thick metal objects. The advantage of using high energy neutrons for radiographic examination of thick metal objects is their higher penetration power and improved contrast sensitivity. Rather l...

Orbital measurements of neu tro ns by the Lunar Explori ng Neutron Detector (LEN D) onboard the Lunar Reconnaissance Orbiter are being used to quantify the spatial dis tribution of near surface hydrogen (H). In fe rred H concentration maps have low signal-to-noise (SN) and image restoration (IR) techniques are being studied to enhance results. A single-blind. two-phase study is described in whi...