Neutron Cross Section Measurement Using the Associated Particle Technique

<p>The associated particle technique is applied to the D(d.n) He3 reaction, in order to produce a tagged neutron beam of accurately known energy, flux, and direction. The incident deuteron beam is obtained from a 400 Kv positive ion Van de Graaff accelerator. A description is given of the design of a uniform field sector magnet and other equipment associated with the stabilization and calibration of the energy of the incident deuteron beam. A versatile n-He3 coincidence system is described. The use of a silicon surface barrier detector with a thin nickel foil window enables complete resolution of the He3 peak with consequent improved neutron flux determination. The tagged neutron beam is used to measure the absolute neutron cross sections of the K39 (n,p) A39 and K39 (n, alpha) Cl36 reactions at a neutron energy of 2.46 Mev. The results obtained, (95 plus-minus 4) mb and (6.2 plus-minus 1) mb respectively, are compared with values obtained by other workers, and with theoretical predictions.</p>

Neutron Cross Section Measurement Using the Associated Particle Technique

<p>The associated particle technique is applied to the D(d.n) He3 reaction, in order to produce a tagged neutron beam of accurately known energy, flux, and direction. The incident deuteron beam is obtained from a 400 Kv positive ion Van de Graaff accelerator. A description is given of the design of a uniform field sector magnet and other equipment associated with the stabilization and calibration of the energy of the incident deuteron beam. A versatile n-He3 coincidence system is described. The use of a silicon surface barrier detector with a thin nickel foil window enables complete resolution of the He3 peak with consequent improved neutron flux determination. The tagged neutron beam is used to measure the absolute neutron cross sections of the K39 (n,p) A39 and K39 (n, alpha) Cl36 reactions at a neutron energy of 2.46 Mev. The results obtained, (95 plus-minus 4) mb and (6.2 plus-minus 1) mb respectively, are compared with values obtained by other workers, and with theoretical predictions.</p>

Influence of α-particles irradiation on the properties and performance of silicon semiconductor detectors

Deterioration of the operation parameters of p-type Si surface-barrier detector and Si(Li) p-i-n detector upon irradiation by alpha-particles was investigated. The detectors were irradiated at room temperature up to a total number of the registered α-particles Nα equal to 6 × 109. Prolonged irradiation has resulted in a deterioration of the detectors energy resolution ability and it was found that the increase of α-peaks broadening can be described by a linear function of Nα with a slope Δσ/ΔNα ∼ (1.4–1.8) × 10–9 keV/α for both detectors. Resolution deterioration was associated with the increase of the detectors leakage current, which proceeds linearly with the number of absorbed α-particles with the slope ΔI/ΔNα ∼ (7-17) × 10-17 A/α. The increase of the detectors reverse current was related with appearance of radiation-induced defect level at 0.56 eV above the valence band.

PADC response to 0.3 - 3 MeV protons

Two types of Poly-Allyl-Diglycol Carbonate, the Neutrak and PN3 were investigated using track diameter distribution induced by the monoenergetic protons with energies in the range of 0.3 to 3 MeV. The energies and intensities were controlled by a silicon surface barrier detector and a nickel scattered foil placed in a 4 MV Van der Graaf accelerator. After different etching times, the etch track-sizes were scanned and measured with the optical microscope. PN3 and Neutrak track diameter responses to protons were measured, plotted, and discussed as a function of energy.

A finite element simulation of transition-edge sensor for measuring kinetic energy of fission fragments

It is necessary to accurately measure the kinetic energy of fission fragments when using the Time-Of-Flight method to determine the mass of fission fragments. The ionization chamber and the Au-Si surface barrier detector are conventional kinetic-energy detectors, but their energy resolution is not sufficient to achieve a mass resolution of 1 amu. The Transition-Edge Sensor (TES) is a cryogenic calorimeter that can be used to measure the kinetic energy by measuring the temperature variation induced by the energy of the incident particle, with a typical resolution of 0.02% of TES detector can be achieved[1]. In this article, we designed a TES to measure the kinetic energy of fission fragments, and the signals of this TES with different incident particle positions, kinetic energy, and thermal conductivity were simulated using ANSYS. Therefore, we verified the feasibility of the TES and improved the count rate of the TES to 100cps.

Numerical Analysis of Dark Currents in T2SL nBn Detector Grown by MBE on GaAs Substrate

The paper presents the numerical analysis of the performance of the nBn type-II superlattice barrier detector operated at 230 K. Results of theoretical predictions were compared to the experimental data for the nBn detector composed of AlAs0.15Sb0.85 barrier and InAs (5.096 nm)/InAs0.62Sb0.38 (1.94 nm) superlattice absorber and contact layer. Detector structure was grown on GaAs substrate using molecular beam epitaxy. To determine the position of the electron miniband and the first heavy hole state in the superlattice, we have used a k·p model which can also predict the absorption spectrum and the cut-off wavelength of an absorber layer. As shown, the most important parameters in the nBn structure optimization is the barrier height in the valence band. While the barrier in the conduction band must be high enough to prevent the flow of the electron current from the contact layer to the absorber, the barrier in the valence band must be sufficiently low to ensure the flow and a collection of optically generated holes. The position of the valence band edge for the AlAsSb barrier was changed by changing the valence band bowing parameter for this ternary material. Proper fit of the calculated plot to our experimental data was obtained assuming no bowing in the valence band for AlAsSb barrier.

INVERSE KINEMATICS AND PID CONTROLLER IMPLEMENTATION OF HEXAPOD ROBOT FOR WALL FOLLOWER NAVIGATION

Wall following is one of the methods used in navigating the movement of robot applications. Because the robot moves along the wall, the ultrasonic sensor is used as a barrier detector capable of measuring the distance between the robot and the wall. The six-legged robot is a hexapod robot has six pieces of legs and each leg has three joints that are used to move. The leg movement is based on the inverse kinematics to obtain the angle value of each joint. Nevertheless, a six-legged robot requires stability in order to move smoothly while following the wall. In this work, a robot was developed using a proportional derivative controller to implemented on wall follower navigation. The PID controller is determined using analytic tuning to produce the controller parameters that are used to make the robot move straighten and keep the position against the wall. Overall, the application of inverse kinematics and PID control on the wall following robot navigation can improve the stability of the robot with a set point value of 8-16 cm on the wall length of 1.5 within 92–96 % of average success rate.