[en] Ultra-relativistic heavy ion collisions will create, by highly compressing nuclei, a new state of matter in which quarks are not bound any more but freed from their confining within nucleons. This form of matter called quark-gluon plasma or QGP will be studied with the ALICE experiment at the CERN LHC. This work describes the V0 detector which is composed of two scintillator hodoscopes located in either sides of the beam collision point in the center of the ALICE detector. The V0 detector plays a major role in ALICE. It provides the level 0 trigger of the experiment, it eliminates most of the instrumental background. It measures the luminosity in proton-proton collisions. The detector design and performance are detailed. Dimuon physics is then investigated by studying low-mass resonances. Indeed the invariant mass region below 3 GeV/c² provides important information about the hot and dense matter created in ultrarelativistic heavy ion collisions. The features of the low-mass resonance ρ⁰, ω and φ⁰ and their possible modifications might be a consequence of restoring chiral symmetry and therefore be interpreted as a signature for the formation of the new state of matter, the Quark Gluon Plasma. The capability of observing these resonances in p-p and Pb-Pb modes using the ALICE dimuon spectrometer, via their muon pair decays, is estimated. (author)

[en] In this paper we have studied the He⁶ production in the two-stage system (neutron converter - ion production targets) for the EURISOL-DS needs. Following the baseline parameters, we have worked in more detail on thermal and neutron flux observables for a system composed of a Tungsten or Tantalum converter, surrounded by a BeO target. Incident proton beam has been fixed to 1 GeV with a 100 kW power. We have confirmed that this initial configuration does not allow reaching the desired He⁶ production rate in the target, i.e. we have obtained 2*10¹³ ions/s compared to 2*10¹⁴ ions/s. A number of geometry, material and incident beam parameters have been optimized with the goal to increase the production rate by a factor of 10. For this purpose we have used the MCNPX code. We have showed that a gain factor of 5 compared to the initial reference configuration can be obtained, i.e. the final He⁶ production rate is about 1*10¹⁴ He⁶/s. We add that further increase in production of He⁶ ions could be achieved 'simply' by increasing the external BeO target radius, i.e. by increasing the volume of production target. On the other hand, such a geometry modification would certainly induce He⁶ on-line extraction losses, i.e. the final increase in available He⁶ ion beam is not guaranteed. Additional studies on the extraction efficiency should be done shortly

[en] We have used MCNPX coupled to CINDER to estimate the production of radioactive nuclides in the EURISOL 4 MW liquid mercury target during a 40 years'lifetime of the installation. The calculations have been done with different intra-nuclear cascade and fission evaporation model combinations. A benchmark exercise has allowed a better understanding of differences seen between these models for the creation of tritium and fission products. To obtain a realistic production yield for tritium gas in proton induced spallation reactions, we recommend using the ISABEL-RAL model, while both CEM2k and BERTINI-RAL overestimate the production rate above 1 GeV incident proton. The best combinations of models to calculate the residual nuclei production are those using ABLA fission-evaporation model, CEM2k or combinations using RAL model are giving too broad mass distributions when compared to available data. An extensive list of radio-nuclides was obtained and is available on tabular format, we show that the 4 nuclei whose contributions to the total activity of the mercury target (after 40 years of irradiation) are the most important are the following: -) 1 day after shutdown: Y⁹¹ (15%), Y⁹⁰ (13%), Hg¹⁹⁷ (6%) and Sr⁸⁹ (5%); -) 1 year after shutdown: H³ (19%), Y⁹⁰ (17%), Sr⁹⁰ (17%) and Nb^93* (10%); -) 10 years after shutdown: Y⁹⁰ (22%), Sr⁹⁰ (22%), H³ (18%) and Nb^93* (14%); and -) 100 years after shutdown: Mo⁹³ (34%), Nb^93* (32%), Pt¹⁹³ (9%) and Y⁹⁰ (8%). (A.C.)

[en] We have begun this benchmark study using mass distribution data of reaction products obtained at GSI in inverse kinematics. This step has allowed us to make a first selection among 10 spallation models; in this way the first assessment of the quality of the models was obtained. Then, in a second part, experimental mass distributions for some elements, which either are interesting as radioactive ion beams or important due to the safety and radioprotection issues (alpha or gamma emitters), will be also compared to model calculations. These data have been obtained for an equivalent 0.8 or 1.0 GeV proton beam, which is approximately the proposed projectile energy. We note that in realistic thick targets the proton beam will be slowed down and some secondary particles will be produced. Therefore, the residual nuclei production at lower energies is also important. For this reason, we also performed in the third part of this work some excitation function calculations and the associated data obtained with gamma-spectroscopy to test the models in a wide projectile energy range. We conclude that INCL4/Abla and Isabel/Abla are the best model combinations which we recommend. We also note that the agreement between model and data are better with 1 GeV protons than with 100-200 MeV protons

[en] Within the Euramet JRP7 project External Beam Cancer Therapy, a work package was dedicated to the primary standards for IMRT (intensity modulated radiation therapy). The French national metrology laboratory for ionizing radiations, LNE-LNHB, was involved in determining absorbed dose to water based on graphite calorimeters in 6 MV and 12 MV beams for field sizes of 10 cm * 10 cm, 4 cm * 4 cm and 2 cm * 2 cm. The existing GR-09 graphite calorimeter has been successfully used for the beam sizes of 10 cm *10 cm and 4 cm * 4 cm whereas it was not small enough to perform measurements in the 2 cm * 2 cm beam size. Therefore, during the project a small section graphite calorimeter, GR-10, has been developed. This work deals with the design, construction and tests of this new graphite calorimeter. (authors)

[en] Calorimetry is the best technique available to perform absolute measurement of absorbed dose. Graphite or water calorimeters are mainly used as reference for absorbed dose in water in most of the national metrology laboratories involved in ionizing radiations. LNE-LNHB has a long experience with graphite and tissue-equivalent calorimeters. Graphite calorimeter is nowadays the reference dosimeter for photon and electron beams at LNE-LNHB. Associated with a transfer procedure from graphite to water, it leads to the reference of absorbed dose to water which is the reference quantity for radiotherapy. A water calorimeter is being developed currently in order to compare different ways to establish the standards of absorbed dose to water at LNE-LNHB. (authors)

[en] Graphite and water calorimeters are used to establish absorbed dose standards in most of the national metrology laboratories involved in ionizing radiation dosimetry. To date, a graphite calorimeter is the reference dosimeter for radiotherapy photon beams at Laboratoire National Henri Becquerel (LNE-LNHB). A new water calorimeter has been developed in order to compare different ways to establish the absorbed dose to water. This paper describes this new calorimeter and the results obtained in the laboratory ⁶⁰Co beam. The LNE-LNHB can now operate both graphite and water calorimetry, and thus has two independent methods to measure the absorbed dose to water. (author)

[en] Calorimetry is the best technique available to perform absolute measurement of absorbed dose, The energy imparted by ionizing radiations to the mater by mass unit is directly measured, matching the definition of the absorbed dose quantity, Graphite or water calorimeters are mainly used as reference for absorbed dose in water in most of the national metrology laboratories involved in ionizing radiations. LNE-LNHB has a long experience with graphite and tissue-equivalent calorimeters. Graphite calorimeter is still the reference for photon and electron beams dosimetry. Associated with a transfer procedure from graphite to water, it leads to the reference of absorbed dose to water which is the reference quantity for radiotherapy. The new water calorimeter built mainly consists of a water filled acrylic glass container enclosed in a thick layer of polystyrene. The double wall container is regulated in temperature at 4^oC to avoid convection in the water volume. The temperature rise is measured with a thermistor probe positioned inside a quartz vessel containing high purity water. Heat transfers inside the calorimeter were simulated with a finite elements software in order to improve the design of the different elements ensuring thermal control of the water acrylic phantom. Thermal simulation and absorbed dose distribution simulation by Monte-Carlo method have been used to evaluate the correction factor due to thermal conduction. The perturbation factor of the radiation field caused by the calorimeter materials has been determined both by ionization chamber measurement and Monte-Carlo calculations. In water, all the energy deposited by radiation is not converted in thermal heat, depending of the content in gases and impurities (heat defect of water). In order to obtain a zero heat defect, high purity water saturated with N₂ gas is used to fill the measurement quartz vessel. Simulations of the water radiolysis, based on real measurements, have been used to estimate the uncertainty on the heat defect which is the major term of the uncertainty budget. The new LNE-LNHB water calorimeter has been used in ⁶⁰Co beam. Measurements under irradiation will be exposed in details and the related uncertainties will be analyzed. The results are compared with the reference of absorbed dose to water established with other primary methods. Absorbed dose to water measured by water calorimeter presents a dispersion between 1 and 2% but the automation of measurements allows to reduce the uncertainty on the mean value to 0.07% by carrying a large number of irradiations (N=420). The results are in good agreement with the present reference based on graphite calorimetry. The final combined relative standard uncertainty on absorbed dose to water is 0.49%. The new water calorimeter allows a measurement of the absorbed dose to water with a relative standard uncertainty lower than 0.5% complementary to the existing graphite calorimeters. This instrument permits to check the consistency of the laboratory dosimetric references by two independent methods. It is very valuable to operate both graphite and water calorimetry at LNE-LNHB to have a different approach in photon and electron beams for radiotherapy purposes. It will now be used to participate to the new references on accelerator high energy X-ray and electron beams, medium X-ray and proton beams

[en] Purpose: The use of a primary dosimeter larger than the radiation field gives access to the integral of dose over a specified surface normal to the beam. If a relative dose profile of the beam is well known, it is then possible to calculate the distribution of the absorbed dose at any point on the considered surface. This study aims at validating the use of EBT3 gafchromic films for the measurement of 2D dose distribution and integrals of dose in small fields for such use. Methods: New EBT3 films have been fully characterized: the response versus energy, dose-rate and dose has been investigated. Profiles measured in circular field with a diameter of 20 mm have been compared to the ones measured with a diamond detector developed at CEA/LIST/LCD. The ratio of dose area products measured with EBT3 on a 6 mm and 30 mm diameter surface has been compared to the ratio measured with primary dosimeters (calorimeters) and calculated with Monte Carlo simulations. Results: There was no significant difference between the dose-calibration curves in a 6 MV and a 60Co beam. Deviation was within uncertainty bars when the dose rate inside a pulse was divided by a factor of 80 in the 6 MV photon beam. Profiles in small fields are in good agreement with the diamond profiles. Dose area product ratios obtained with EBT3, calorimeters and simulations are within 1%. Conclusion: EBT3 films are good candidates for the measurement of relative dose distribution in small fields as long as the average of several films is considered. They can be used in association with primary measurements to determinate dosimetric references in small fields and to transfer them to the end user

[en] The LNE-LNHB has developed two primary standards to determine the absorbed dose to water under reference conditions (for 10 cm * 10 cm) in ⁶⁰Co, 6 MV, 12 MV and 20 MV photon beams: a new graphite calorimeter and a water calorimeter. This first paper presents the results obtained with the graphite calorimeter and the new associated methodology. The associated relative standard uncertainty (k = 1) of absorbed dose to water is 0.25% for ⁶⁰Co and lies between 0.32% to 0.35% for MV X-ray beams. (authors)