Introduction: In radiation therapy with high-energy photon beams (E > 7 MeV) neutrons are generated mainly in LINACs head thorough (γ, n) interactions. These neutrons affect the shielding requirements in radiation therapy rooms. According to the protocol TG-34, photon absorbed dose of 10Gy can cause permanent damage to the pacemaker and the dose of 2Gy can make minor changes in...

X-ray observations suggest that neutron stars in low mass X-ray binaries (LMXB) are rotating with frequencies from 300 600 Hz. These spin rates are significantly less than the break-up rates for essentially all realistic neutron star equations of state, suggesting that some process may limit the spin frequencies of accreting neutron stars to this range. If the accretion induced spin up torque i...

Many people are experienced in measuring radiation dose from photons and electrons. These two forms of radiation involve similar measurements since it is secondary electrons produced by the photons which actuallv deliver the dose. The electron is a light charged particle. Relatively fewer people have experience in measuring neutron dose. The neutron is a heavy uncharged particle. It has nearly ...

@ Neutron and gamma radiation levels around a Cockcroft-Walton neutron generator producing 14-Mev neutrons at an approximate rate of 1010 neutrons per second were measured under conditions typical of those required for activation analysis. Neutron flux reduction to acceptable levels for limited operation was accomplished by 12 feet of distance that included shielding consisting of 27 inches of ...

Simple arguments concerning power and acceleration efficiency show that ultra-high energy cosmic rays (UHECRS) with energies > ∼ 10 eV could originate from GRBs. Neutrons formed through photo-pion production processes in GRB blast waves leave the acceleration site and travel through intergalactic space, where they decay and inject a very energetic proton and electron component into intergalacti...

Accreting black holes and neutron stars at luminosities above 0.01 of the critical Eddington luminosity have a lot of similarities, but also drastic differences in their radiation and power density spectra. The efficiency of energy release due to accretion onto a rotating neutron star usually is higher than in the case of a black hole. The theory of the spreading layer on the surface of an accr...

In present work, the SHIELD code system have been used to investigate the physics properties of spallation neutron target, such as the neutron spectra, the yield, the radioactivity in the target and the target size etc. The fragment mass distribution of the residual nuclei from proton-induced spallation reaction on thick lead target with energy 1.6 GeV have been analysed also. Radiation damage,...

medical linear accelerators are one of the most widespread methods for cancer treatment. despite their advantages, unwanted photoneutrons are produced by high energy linacs. this photoneutrons are as undesired doses to patients and a significant problem for radiation protection of the staffs and patients. photoneutrons radiological risk must be evaluated because of their high let and range.in o...

Recent advances in combined modality treatment of locally advanced head and neck cancer have improved local and regional disease control and survival with better functional outcome. However, the local and regional failure rate after radiation therapy is still high for tumors that respond poorly to cisplatin-based neoadjuvant chemotherapy. This clinical observation suggests a common biological m...

Introduction: GRID therapy is a treatment modality in which a high dose of radiation in a single fraction is given to the tumor. This technique previously was used to treat bulky tumors with orthovoltage beams. Recently, studies have been conducted to suggest that GRID therapy with megavoltage photons can be useful in palliative treatments. On the other hand, there has always ...