In the beam pipe of the positron damping ring of the Next Linear Collider, electrons will be created by beam interaction with the surrounding vacuum chamber wall and give rise to an electron cloud. Several solutions are possible for avoiding the electron cloud, without changing the bunch structure or the diameter of the vacuum chamber. Some of the currently available solutions for preventing th...

in this study, a general theoretical model to foresee and calculate the current-voltagecharacteristics in a plateau zone and the associated efficiency of the neutron detector (sensitivity) is presented. this study is to complete the previous studies in this field. the model also considers electric field distortion resulting from the charge collection effect. the characteristics curve is obtaine...

Calibrations of two tissue equivalent (TE) ionization chamber were made in five photon beams (100 kV, 180 kV, 250 kV, Cs and Co) with two different pure gases namely acetylene C2 H2 and carbon dioxide CO2. The different calibration factors were compared both for in-air and in-water phantom, the measurements were performed according to the international atomic energy agency (IAEA) recommendation...

[1] We have studied sulfuric acid aerosol nucleation in an atmospheric pressure reaction chamber using a 580 MeV electron beam to ionize the volume of the reaction chamber. We find a clear contribution from ion‐induced nucleation and consider this to be the first unambiguous observation of the ion‐effect on aerosol nucleation using a particle beam under conditions that resemble the Earth’s atmo...

The 68Ga generator, obtained from New England Nuclear, Boston MA, USA through the Japan Radioisotope Association, uses 68Ge fixed by tin dioxide (SnO2) and placed in a glass column. This column is connected to inlet and outlet tubes and placed in a small lead casing. The generator activity was measured by an ionization chamber from the top (the top shield was removed for measurements). The elua...

When the PDD (percentage depth dose) in the megavoltage beams is measured in the water phantom using the dosimetry system, the polarity and ion recombination effects of ionization chambers with depth in water are not usually taken into consideration. The polarity and ion recombination effects may vary depending on the radiation type and spectrum, which vary with depth in water [1-4]. If those e...

Air kerma calibration coefficients for a reference class ionization chamber from narrow x-ray spectra and cesium 137 gamma-ray beams were compared between the National Institute of Standards and Technology (NIST) and the Kenya Bureau of Standards (KEBS). A NIST reference-class transfer ionization chamber was calibrated by each laboratory in terms of the quantity air kerma in four x-ray referenc...

The computed tomography dose index (CTDI) measured with a 10 cm long pencil ionization chamber placed in a 14 cm long PMMA phantom is typically used to evaluate the doses delivered during CT procedure. For the new generation of CT scanners, the efficiency of this methodology is low because it excludes the contribution of radiation scattered beyond the 100 mm range of integration along z. The AA...