Abstract Mutations in the gene encoding 27-kDa small heat-shock protein B1 ( HSPB1 ) have been reported in association with Charcot-Marie-Tooth disease type 2F or dHMN type II. We describe an Italian ...patient with wasting and weakness of distal muscles, involving primarily and mostly the lower limbs and later the upper limbs, in which a novel mutation of HSPB1 , T180I, was detected. Electrophysiological evaluation disclosed a pure motor axonal neuropathy. Sural nerve biopsy showed a mild reduction of myelinated fibre density. All these findings suggested a CMT2/dHMN phenotype.
Bonner Spheres Spectrometry in its high-energy extended version is an established method to quantify neutrons at a wide energy range from several meV up to more than 1 GeV. In order to allow for ...quantitative measurements, the responses of the various spheres used in a Bonner Sphere Spectrometer (BSS) are usually simulated by Monte Carlo (MC) codes over the neutron energy range of interest. Because above 20 MeV experimental cross section data are scarce, intra-nuclear cascade (INC) and evaporation models are applied in these MC codes. It was suspected that this lack of data above 20 MeV may translate to differences in simulated BSS response functions depending on the MC code and nuclear models used, which in turn may add to the uncertainty involved in Bonner Sphere Spectrometry, in particular for neutron energies above 20 MeV. In order to investigate this issue in a systematic way, EURADOS (European Radiation Dosimetry Group) initiated an exercise where six groups having experience in neutron transport calculations with the MC codes (MCNP, MCNPX, FLUKA, PHITS, MARS, or GEANT4) calculated the responses of a bare 3He proportional counter, a 3He proportional counter embedded in the middle of a 9 inch polyethylene sphere, and a 3He proportional counter centred in a 9 inch polyethylene sphere containing a lead shell, at neutron energies of 1, 10, 100, and 1000 MeV. In general, calculated responses agreed very well for neutron energies below 20 MeV, whatever MC code used. At higher energies, however, certain differences were observed among the different calculations, which may mainly be attributed to the application of different INC models and their parameters. It was found that up to 1 GeV most of the results ranged between calculations previously published that were obtained with MCNP/LAHET using the Bertini INC model and GEANT4 using the Binary and Bertini INC models. These results indicate that use of different MC codes and INC models for the calculation of BSS response functions may result in an uncertainty of unfolded neutron fluences above 20 MeV of about 20%.
•We use Monte Carlo codes to simulate the response function of Bonner spheres.•The codes include different nuclear models at energies between 1 MeV and 1 GeV.•The results agree below 20 MeV but show significant differences above.•These differences contribute to uncertainties in Bonner sphere neutron spectrometry.
The double differential particle yield produced by hadron beams striking thick targets of copper, tungsten and ICRU tissue, have been determined by means of the Monte Carlo transport code FLUKA ...(version FLUKA 2008.3b.1). 400
MeV/u carbon ion and 250
MeV proton pencil beams have been considered. Secondary neutrons, photons, and protons have been scored. In order to validate the obtained data, a few simulations have been also repeated with MCNPX 2.6.0. The calculated results are presented and compared with the experimental data reported in literature. They should be very useful to solve a number of problems related to technological aspects of hadrontherapy.
Study of a radiator degrader CR39 based neutron spectrometer Caresana, M.; Ferrarini, M.; Pola, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2010, Volume:
620, Issue:
2
Journal Article
Peer reviewed
The paper describes the experimental characterization of a neutron spectrometer based on a CR39 SSNTD coupled to a polyethylene radiator and an aluminium degrader.
The response function of the ...spectrometer is calculated by using two analytical codes: the first one, written in Labview, permits to evaluate the critical angle of a particle (proton, alpha or recoil nucleus) impinging on the detector surface, as a function of the particle energy; the second code, written in Mathcad, calculates the recoil proton distribution generated by a monoenergetic neutron beam impinging on the polyethylene converter. The simulation software also accounts for the self radiator effect due to the recoil protons and to the oxygen and carbon recoil nuclei.
The calculated response functions are compared with experimental data showing a fairly good agreement. Also the experimental reproducibility is satisfactory.
The European Commission has funded within its 6th Framework Programme a three-year project (2005–2007) called CONRAD,
COordinated Network for RAdiation Dosimetry. A major task of the CONRAD Work ...Package “
complex mixed radiation fields at workplaces” was to organise a benchmark exercise in a workplace field at a high-energy particle accelerator where neutrons are the dominant radiation component. The CONRAD benchmark exercise took place at the Gesellschaft für Schwerionenforschung mbH (GSI) in Darmstadt, Germany in July 2006. In this paper, the results of the spectrometry using four extended -range Bonner sphere spectrometers of four different institutes are reported. Outside Cave A the neutron spectra were measured with three spectrometers at six selected positions and ambient dose equivalent values were derived for use in the intercomparison with other area monitors and dosemeters. At a common position all three spectrometers were used to allow a direct comparison of their results which acts as an internal quality assurance. The comparison of the neutron spectra measured by the different groups shows very good agreement. A detailed analysis presents some differences between the shapes of the spectra and possible sources of these differences are discussed. However, the ability of Bonner sphere spectrometers to provide reliable integral quantities like fluence and ambient dose equivalent is well demonstrated in this exercise. The fluence and dose results derived by the three groups agree very well within the given uncertainties, not only with respect to the total energy region present in this environment but also for selected energy regions which contribute in certain strength to the total values. In addition to the positions outside Cave A one spectrometer was used to measure the neutron spectrum at one position in the entry maze of Cave A. In this case a comparison was possible to earlier measurements.
A passive neutron rem counter using a CR39 SSNTD coupled with a boron converter has been developed. The rem counter is a polythene sphere with cadmium and lead insets, designed to have a response ...function proportional to the fluence to ambient dose equivalent conversion coefficients, H*(10)/Φ, for energies ranging from thermal up to 1
GeV. At its centre is a thermal neutron detector made of a CR39 SSNTD coupled with an enriched boron neutron converter. The rem counter was first calibrated at CERN and at the Politecnico di Milano, and then tested in high-energy neutron fields at GSI, Darmstadt, Germany and at the CERF facility at CERN. Its most important features are a very high neutron sensitivity and conversely a complete insensitivity to gamma radiation.
Our concept of the pathogenesis of chronic lymphocytic leukemia has undergone remarkable changes during the past decade. This review addresses the latest ideas concerning the origin of this common ...form of leukemia and discusses how molecular investigations are beginning to change the management of the disease.
In this article, the in vivo study performed to evaluate the uniformity of biological doses within an hypothetical target volume and calculate the values of relative biological effectiveness (RBE) at ...different depths in the spread-out Bragg peak (SOBP) of the new CNAO (National Centre for Oncological Hadrontherapy) carbon beams is presented, in the framework of a typical radiobiological beam calibration procedure. The RBE values (relative to (60)Co γ rays) of the CNAO active scanning carbon ion beams were determined using jejunal crypt regeneration in mice as biological system at the entrance, centre and distal end of a 6-cm SOBP. The RBE values calculated from the iso-effective doses to reduce crypt survival per circumference to 10, ranged from 1.52 at the middle of the SOBP to 1.75 at the distal position and are in agreement with those previously reported from other carbon ion facilities. In conclusion, this first set of in vivo experiments shows that the CNAO carbon beam is radiobiologically comparable with the NIRS (National Institute of Radiological Sciences, Chiba, Japan) and GSI (Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany) ones.
LR115 cellulose nitrate SSNTD are routinely used for Radon detection. A reading technique with high resolution optical microscope coupled with a scanning system has been recently proposed.
In this ...technique, the efficiency correction that was formerly performed on the residual thickness of the detector is performed on the track area distribution. So all the information that is needed for the measurement is obtained directly during the scanning. This leads to a much simpler and faster reading procedure, when compared to the classical technique that required both spark counting and micrometer residual thickness measure.
A complete characterization and performance evaluation of the detector response is discussed, including a measuring range evaluation, a combined uncertainty theoretical calculation and a blind test validation at HPA.
