Excitation of the Delta (1232)-Resonance in Proton-Nucleus Collisions

peer reviewe

Space Charge Studies for the Ionisation Profile Monitors for the ESS Cold Linac

International audienceIn this paper, we present the results from a numerical code developed to study the effect of space charge on the performance of Ionisation Profile Monitors. The code has been developed from the analytical expression of the electromagnetic field generated by a 3D bunch of charged particles moving along one axis. This transient field is evaluated to calculate the momentum gained by a test moving particle, but not necessary co-moving with the bunch, and included in a non-linear ordinary differential equation solver (Runge-Kutta) to track the 3D motion of the test particle. The model of the IPM is complete when an additional constant electric field is included to project the test particle onto a screen. The results from this code, modelling the IPM to be developed for the ESS Cold Linac, are presented here, and the impact of the space charge on the measurement of the beam profile is discussed

A New Beam Loss Monitor Concept Based on Fast Neutron Detection and Very Low Photon Sensitivity

International audienceSuperconductive accelerators may emit X-rays and Gammas mainly due to high electric fields applied on the superconductive cavity surfaces. Indeed, electron emissions will generate photons when electrons impinge on some material. Their energies depend on electron energies, which can be strongly increased by the cavity radio frequency power when it is phase-correlated with the electrons. Such photons present a real problem for Beam Loss Monitor (BLM) systems since no discrimination can be made between cavity contributions and beam loss contributions. Therefore, a new BLM is proposed which is based on gaseous Micromegas detectors, highly sensitive to fast neutrons, not to thermal ones and mostly insensitive to X-rays and Gammas. This detector uses Polyethylene for neutron moderation and the detection is achieved using a 10B or 10B4C converter film with a Micromegas gaseous amplification. Simulations show that detection efficiencies > 8 % are achievable for neutrons with energies between 1 eV and 10 MeV

Experimental determination of cesium and iodine speciation in UO2 as a function of temperature and oxygen partial pressure

International audienc

Experimental determination of cesium and iodine speciation in UO2 as a function of temperature and oxygen partial pressure

International audienc

Space Charge Effects Studies for the ESS Cold Linac Beam Profiler

International audienceFive Ionization Profile Monitors are being built by CEA in the framework of the in-kind contribution agreement signed with ESS. The IPMs will be installed in the Cold Linac where the proton energy range they need to cover extends from 90 MeV to 2 GeV. The ESS fields intensity of 1.10⁺⁰⁹ protons/bunch delivered at a frequency of 352 or 704 MHz, with a duty cycle of 4%, may strongly affect the trajectories of the ionized molecules and electrons created by the passage of the beam through the residual gas. In order to quantify and to develop a correction algorithm for these space charge effects, a code was initiated at ESS and completed at CEA Saclay with the possibility to include real case electric fields calculated with Comsol Multiphysics. A general overview of the code and its preliminary results are presented here

Space Charge Effects Studies for the ESS Cold Linac Beam Profiler

International audienceFive Ionization Profile Monitors are being built by CEA in the framework of the in-kind contribution agreement signed with ESS. The IPMs will be installed in the Cold Linac where the proton energy range they need to cover extends from 90 MeV to 2 GeV. The ESS fields intensity of 1.10⁺⁰⁹ protons/bunch delivered at a frequency of 352 or 704 MHz, with a duty cycle of 4%, may strongly affect the trajectories of the ionized molecules and electrons created by the passage of the beam through the residual gas. In order to quantify and to develop a correction algorithm for these space charge effects, a code was initiated at ESS and completed at CEA Saclay with the possibility to include real case electric fields calculated with Comsol Multiphysics. A general overview of the code and its preliminary results are presented here

Ionization Profile Monitor Simulations - Status and Future Plans

International audienceNonuniformities of the extraction fields, the velocity distribution of electrons from ionization processes and strong bunch fields are just a few of the effects affecting Ionization Profile Monitor measurements and operation. Careful analysis of these phenomena require specialized simulation programs. A handful of such codes have been written independently by various researchers over the recent years, showing an important demand for this type of study. In this paper we describe the available codes and discuss various approaches to Ionization Profile Monitor simulations. We propose benchmark conditions to compare these codes among each other and we collect data from various devices to benchmark codes against the measurements. Finally we present a community effort with a goal to discuss the codes, exchange simulation results and to develop and maintain a new, common codebase

Behaviour of fission products in UO2: Experimental characterization of the Cs-I-UO2 model system at high temperature

International audienceThe interactions of iodine and caesium in UO2 have been investigated. For this purpose, implanted UO2 samples were thermally treated (4h at 900°C or 1h at 1200°C) under controlled atmosphere (0.03% H2O/H2) and then characterized by several experimental techniques for their structural and chemical studies. Thermodynamic calculations were also performed in order to optimize heat treatment conditions before performing tests, and to help in the interpretation of results afterwards. The sample characterizations after thermal treatments reveal the presence of bubbles and precipitates (mean diameter around 10 - 20 nm) and have allowed to clearly identify the presence of CsI in these bubbles which is in agreement with the calculations. The chemical form of the observed precipitates is not well defined yet, due to the lack of experimental reference spectra, but they consist very likely of caesium uranates, as predicted by the thermodynamic calculations