[en] The present report summarizes the studies carried out at ENEA-AMB-PRO-IRP (Institute for Radiation Protection) that were addressed to the determination of air kerma to personal dose equivalent conversion coefficients for two practical phantoms as proposed by ICRU (International Commission for Radiation Units and Measurements) and by ISO (International Standard Organization) for photon personal dosimeters' calibration procedure. The analyses, developed using the MCNP Monte Carlo code, were mainly aimed at establishing which of the two proposed phantoms better approximates the ICRU theoretical one. Furthermore a complete tabulation of the conversion coefficients is supplied for monoenergetic photon beams from 20 keV to 1 MeV as well as for the two ISO X-ray reference series Wide Spectrum and Narrow Spectrum. The study has been performed in the framework of the CEC Contract F13P-CT92-0064 'The Measurement of the Spectral and Angular Distribution of External Radiations in Workplace and Implications for Personal Dosimetry

[en] The most recent ICRU recommendations suggest to calibrate photon personal dosemeters on a slab phantom instead of a spherical phantom ads previously proposed. This kind of phantoms due to their geometric characteristics can in principle allow a contemporary calibration of several dosemeters at a time. In this framework, particular attention has to be devoted to the evaluation of the limits of the so-called 'homogeneity area' to be employed. According to the ISO Standard 4037 an homogeneity of the calibration field within 5% (±2.5%) is permissible. A rather detailed analysis on this subject has been therefore carried out using the Monte Carlo code MCNP to evaluate the backscattering profiles on PMMA and water filled PMMA phantoms both for normal and oblique incident radiation. At the same time, some air kerma free in air profiles for seven ISO Narrow and Wide Series beams measured at PTB (Braunschweig Germany) were used to model a more realistic irradiation situation. The calculated data were partially compared with experimental results from other European Laboratories

[en] Ruthenium(III) forms a 1:2 complex with 2-thiobarbituric acid, with an absorption maximum at 338 nm; the molar absorptivity is 1.1 x 10₄ l mol^-₁ cm^-₁ and the Sandell's sensitivity of the reaction is 0.009 l μg cm^-₂ per 0.001 absorbance unit. Beer's law is obeyed for up to 28 μg ml^-₁ of ruthenium. The molar composition of the complex was determined by the molar ratio method and confirmed by means of elemental analysis. Co-ordinate bonding involving the sulphur atom of 2-thiobarbituric acid was proved by infrared spectroscopy. The tolerance of the system to platinum metals and other common cations is reported. A statistical evaluation of the proposed method has been undertaken and a comparison with important spectrophotometric reagents for ruthenium(III) used in recent years is presented. (author)

[en] The present report summarizes the activities concerned with numerical dosimetry as carried out at the Radiation Protection Institute of ENEA (Italian Agency for New Technologies, Energy and the Environment) on photon dosimetric quantities. The first part is concerned with MCNP Monte Carlo calculation of field parameters and operational quantities for the ICRU sphere with reference photon beams for the design of personal dosemeters. The second part is related with studies on the ADAM anthropomorphic phantom using the SABRINA and MCNP codes. The results of other Monte Carlo studies carried out on electron conversion factors for various tissue equivalent slab phantoms are about to be published in other ENEA reports. The report has been produced in the framework of the EURADOS WG4 (numerical dosimetry) activities within a collaboration between the ENEA Environmental Department and ENEA Energy Department

[en] Following the ICRU and ISO documents concerned with the calibration of photon personal dosemeters on slab phantoms, the ENEA Institute for Radiation Protection performed a series of studies aimed at adopting suitable routine procedures. The reference ISO and ICRU slab phantoms for calibrating dosemeters in terms of H_p (10,α) and H_p (0.07,α) have therefore been acquired. A slab phantom should in principle allow the simultaneous calibration of several dosemeters for the whole body. On the other hand, besides the inhomogeneity of the incident beam, it has to be taken into account that the phantom itself is responsible for a spatial dependence of the air kerma backscatter factor along its front face, implying a limitation of the practical calibration area. The results of Monte Carlo homogeneity area calculations are summarised, and validated using ionisation chamber independent mapping, and of a series of TL measurements of the same air kerma backscatter factor profiles are described. (author)

[en] The Institute for Radiation Protection of ENEA has employed for many years a solid state nuclear track detector CR-39 as a fast neutron personal dosemeter with good results. The 1990 recommendations of ICRP 60 has introduced new parameters to neutron dosimetry that require harmonisation of the dosemeters' response within international recommendations. This paper reports the results of an experimental study performed at ENEA in order to investigate the dosimetric performance of two kinds of CR-39 produced in UK and Italy. Sensitivity, lowest detectable dose, background, linearity, energy and angular responses are compared between the two CR-39 materials. Irradiation tests have been performed with monoenergetic neutron beams in the range from 100 keV to 20 MeV, as well as with ²⁵²Cf and ²⁴¹Am-Be sources. The Italian CR-39 material, used elsewhere for heavy ions detection in scientific applications, has here been comprehensively tested for neutron dosimetry purposes. Results were very satisfactory and it has therefore been introduced in the ENEA Personal Dosimetry Service. (author)

[en] This paper describes a sensitive method for the determination of ruthenium(III) and palladium(II) in mixtures (up to 16 μg ml^-1 of ruthenium and 4.5 μg ml^-1 of palladium) by first and second derivative spectrophotometry. The method is based upon the coloured complexes that both ruthenium and palladium form with 2-thiobarbituric acid. A statistical analysis of the experimental results is presented. (author)

[en] The ENEA fast neutron dosemeter is based on a planar PADC (poly allyl diglycol carbonate) placed in a polyethylene holder. The CR-39 (registered trademark of PPG Industries Inc.) material, produced by Intercast Europe S.p.A., has been used in the routine of the Individual Monitoring Service (IMS) since 1998. Since then, acceptance test on average sheet background track density and sheet neutron sensitivity have been made on new batches as a quality control within a quality assurance programme of the IMS of ENEA-Institute for Radiation Protection (IRP). Dosemeters were irradiated with a ²⁴¹Am-Be source at ENEA-IRP and processed through a chemical etching procedure (pre-etching with 40% KOH water solution 6.25 M and 60% ethyl alcohol at 70 deg. C followed by 12 h of etching in 6.25 M KOH water solution). In this paper we present the analysis of acceptance testing data for more than 30 sheets of CR-39 plastic produced in 1998, 1999 and 2000. Moreover, we compare the performance of sheets of CR-39 of standard composition with that of sheets of CR-39 with the addition of DOP (dioctylphthalate), in different concentrations, on the basis of average background density, neutron sensitivity and background fluctuation that limit the lower detectable dose. This study demonstrates the need for acceptance tests to assure the quality of the dosimetric performance of these dosemeters, which is considerably dependent on the quality of the CR-39 plastic. (author)

[en] The computed field parameters, collision kerma backscatter factor, backscattered radiation mean energy and their dependence on radiation incident angle as well as the ICRU operational quantities directional dose equivalents H'(0.07,ω), H'(3,ω) and H'(10,ω) have been computed for a spherical phantom composed by the tissue substitute material RS-1, which demonstrated its very similar characteristics to the ICRU theoretical material. The calculations have been carried out with the Monte Carlo code MCNP (Monte Carlo for Neutrons and Photons). These data together with energy response experimental data allow the optimisation in the design procedure of personal dosemeters in terms of the new operational quantities as defined by ICRU 39-43 in the energy range from 20 to 1250 keV

[en] A new ENEA dosemeter based on two TL detectors, LiF(Mg,Cu,P) (GR-200) and ⁷LiF(Mg,Cu,P) (GR-207), was investigated. The different thermal neutron and gamma sensitivities of the two detectors allow a good dose equivalent estimation in mixed n-γ fields. The higher sensitivity of both detectors as compared with LiF(Mg,Ti) and ⁷LiF(Mg,Ti) detectors, currently used at ENEA for routine personal dosimetry, allows a lower dose equivalent threshold to be achieved as well as a better discrimination of the neutron and gamma components of the radiation field. A dose calculation algorithm was developed and assessed by experimental tests performed both at ENEA Institute for Radiation Protection thermal neutron irradiation facility as well as at the IPSN SIGMA facility in Cadarache (France). The intercalibration test supplied the necessary guidelines for future routine dosemeter calibrations. Our results demonstrated that the new dosemeter can easily replace the currently employed dosemeter for mixed thermal neutron and gamma fields in routine personal dosimetry. (author)