نتایج جستجو برای: photon

تعداد نتایج: 70717  

Journal: :iranian journal of science and technology (sciences) 2011
m. m. golshan

in this work we investigate the thermal entanglement between two-level atoms and photons in a nonlinear cavity. we consider intensity-dependent couplings and calculate the negativity, as a measure of atom-photonentanglement. the cavity is assumed to be at a temperature t, so that all number of photons, and at the same time, both atomic states, with definite probabilities, are present. we then d...

E. Asadi Amirabadi, H. Afarideh, H. Ghafoorifard, M. Asgari,

Background: Polymer composites when reinforced with heavy metals in the form of micro/nano particles are efficient gamma- and X-ray shielding materials providing such advantageous features as cost-effectiveness, light-weight factor, flexibility, non-toxicity, conformability over conventional shields. Materials and Methods: In this paper the influence of weight percentages and particle sizes of ...

Journal: :iranian journal of nuclear medicine 2004
nasrollah jabbari hossein rajabi hassan firoozabadi fereidoon rastgoo nahid yaghoobi

introduction: scatter radiation is one of the major sources of error in nuclear medicine data processing. different methods of scatter correction have been introduced in order to improve the quality of data. however the best method is to avoid recording of scatter photons in acquisition. the only difference between scattered and non-scattered photons is the energy. pulse height analyzer is the ...

Seventeen two-photon transitions for neon have been observed in the 580- 635 nm spectral region for use in the spectroscopic study of its higher excited levels, which are not accessible by one-photon absorption. To compare the two and one-photon absorption signals originating from the same lower level, an effort was made to record single-photon optogalvanic spectrum in the available wavele...

D. Demir, G. Yegin, H.O. Tekin, I. Akkurt, K. Gunoglu, Z.N. Demirci,

Background: As bremsstrahlung photon beam fluence is important parameter to be known in a photonuclear reaction experiment as the number of produced particle is strongly depends on photon fluence. Materials and Methods: Photon production yield from different thickness of aluminum target has been estimated using artificial neural network (ANN) model. Target thickness and incoming electr...

احمد شیرانی, , محمد حسن علامت ساز, ,

  Monte Carlo simulation is widely used in calculations involing transport of photons through different materials of different shapes. The method consists of randomly generating a finite set of photon histories over which the quantities of interest are averaged. In photon transport calculations, sampling the photon scattering angle from the Klein-Nishina probability distribution is of special i...

Journal: :iranian journal of cancer prevention 0
a iftikhar center for nuclear medicine and radiotherapy (cenar), bmc complex, quetta, pakistan m wazir institute of nuclear medicine, oncology and radiotherapy, abbotabad, pakistan mb kakakhail pakistan institute of engineering and applied sciences (pieas) islamabad, pakistan a sbilal pakistan institute of engineering and applied sciences (pieas) islamabad, pakistan a khwaja center for nuclear medicine and radiotherapy (cenar), bmc complex, quetta, pakistan a khushnaseeb center for nuclear medicine and radiotherapy (cenar), bmc complex, quetta, pakistan

background: during radiotherapy treatment, critical organs are shielded using lead and cerrobend blocks. the objective of this study is to compare the effects of lead and cerrobend shielding blocks on incident photon beam. methods: collimator scatter factors were measured for open square fields (3 x 3 cm to 40 x 40 cm) defined by collimator jaws and for fields blocked down to smaller asymmetric...

Journal: :iranian journal of radiation research 0
s. barlaz us mersin university, faculty of medicine, department of radiation oncology, mersin, turkey e. kaya pepele inonu university, faculty of medicine, department of radiation oncology, malatya, turkey

background: the purpose of this study was to investigate the various gantry angle and ssd dependencies of tld and mosfet dosimeters. materials and methods: lif (mg) tld and mosfet were used in this study. dosimeter systems were calibrated and then irradiated at various gantry angle and ssd by applying 6 mv photon energy. results: based on the results, mosfet changes were found to be in 2% range...

M. Keshtkar, M. Saeb, N. Rostampour, P. Shokrani, S. Jafari, T. Almasi,

Background: Skyshine describes the radiation scattered by the atmosphere above a LINAC facility to a point on the ground. The aim of this study was to measure the skyshine photon dose rates from two different (9 MV and 18 MV) medical linear accelerators. Materials and Methods: The photon beam was directed upward (180° gantry position), with a maximum photon field size (40 × 40 cm2) at the isoce...

Journal: :Le Journal de Physique Colloques 1982

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