Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Powiadomienia systemowe

Sesja wygasła!

Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: Monte Carlo calculations

Sortuj według:

Ogranicz wyniki do:

Feasibility of Monte Carlo modelling for the neutron-neutron logging tool response in specific geological models

Wiącek U., Woźnicka U.

Geology, Geophysics and Environment

2016

Vol. 42, no. 3

365--383

Neutron well logging is one of the basic methods for the determination of the characteristic parameters of rock samples. The neutron source and neutron detectors are elements of Neutron-Neutron Thermal-Epithermal logging tool (NNTE) of significant importance. A neutron source creates the neutron field in the nearest environment. Detectors placed at specified distances from the source register neutrons from this space. A signal of a Neutron-Neutron Thermal-Epithermal tool in specific geological conditions was numerically calculated by means of the Monte Carlo (MC) codes. The main aim of this paper is to show the potential for using the Monte Carlo N-Particle Transport Code (MCNP) software in nuclear well logging prospection methods. The results of this MC modelling are presented in this paper.

Influence of the energy spectrum and spatial spread of proton beams used in eye tumor treatment on the depth-dose characteristics

Konefał A., Szaflik P., Zipper W.

Nukleonika

2010

Vol. 55, No. 3

313-316

The influence of the energy spectrum and the spatial spread of a therapeutic proton beam impinging on an irradiated medium (called the entrance beam) on the depth-dose characteristics in water, in the proton energy range of 50 division sign 70 MeV was studied. It turns out that full width at half maximum (FWHM) of the Bragg peak increases almost linearly with increasing proton energy. It ranges from 1.53 mm for 50 MeV to 2.59 mm for 70 MeV, for monoenergetic protons. Moreover, the significant influence of the energy spread of the entrance proton beam on the intensity and FWHM of the Bragg peak is visible. FWHM of the Bragg peak of 60 MeV protons is equal to 2.03, 3.37 and 5.86 mm for a monoenergetic beam and beams with an energy spread of 0.5 and 1 MeV SD (standard deviation), respectively. The intensity of the Bragg peak of a 60 MeV proton beam with an energy spread of 1 MeV SD is approximately 25% less than that for a monoenergetic beam. Moreover, the Bragg peak shifts to smaller depths as the energy spread of the entrance beam increases. The shift of the peak is about 0.2÷0.3 mm for a beam with an energy spread of 0.5 MeV SD and between 0.4 division sign 0.5 mm for an energy spread of 1 MeV SD, compared with a monoenergetic beam in the energy range from 50 to 60 MeV. However, the spatial spread of the entrance proton beam does not affect significantly the depth-dose characteristic.

A Theoretical Study of the cis-syn Cytosine-containing Pyrimidine Dimers in the Gase Phase and a Water Cluster and a Tautomer-Bypass Mechanism for the Origin of UV-induced Mutations

Danilov V., Leś A., Alderfer J. L.

Polish Journal of Chemistry

2001

Vol. 75, nr 7

1039-1049

A quantum mechanical study of cis-syn cyclobutane cytosine-containing photodimers including the normal and rare tautomeric forms of bases has been performed using the ab initio method at HF/6-31G(d,p), MP2(fc)//HF/6-31G(d,p) and MP2(fc)/6-31G(d,p) levels. It is predicted that in the gas phase all photodimers containing the rare imino form of cytosine are more stable than those containing its normal form. The Monte Carlo study of the hydration for cytosine-consisting dimers showed that the dimer containing the imino form of cytosine is stabilized by water cluster more than that containing its amino forms. As a result, the imino form of cytosine in the cytosine-containing dimer directs the incorporation of adenine in the complementary strand during replicative bypass. Data obtained point to the cytosine tautomerism as a possible mechanism for the origin of UV-induced mutation.