Hf(25=2 \Gamma

The cross-sections for excitation of high-spin isomers 177m 2 Hf(37=2 \Gamma ), 179m 2 Hf(25=2 \Gamma ), 177m Lu(23=2 \Gamma ), 180m Hf(8 \Gamma ) and 178m Ta(7 \Gamma ) by 100, 145, and 500 MeV protons irradiating 181 Ta and 180 Hf targets have been measured by off-line fl-spectroscopy. A radiochemical procedure has been used to separate various chemical elements. The values of isomeric ratio for these protonnucleus reactions have been obtained and compared with the corresponding data for nuclear absorption of stopped ß \Gamma -mesons. The isomeric ratio for excitation of high-spin isomers by protons is about two orders of magnitude less than by stopped pions. PACs numbers:25.40.-h,25.40.Ve,25.60.Dz Typeset using REVT E X (submitted to Physical Review Letters) I. INTRODUCTION The phenomenon of high-spin (10 \Gamma 20¯h) isomer excitation by intermediate- energy particles was observed in the absorption of stopped negative pions by nuclei [1--4]. The abnorma..

Production of non-conventional high specific activity radionuclides for biomedical, toxicological, and environmental purposes

Low- and medium-energy accelerators and sometimes thermal nuclear reactor, allow production of very high specific activity radionuclides (HSARNs) for biomedical, environmental, toxicological and occupational investigations. Specific Activities of the order of GBq·μg-1 are achieved; this means that the experiments can be carried out in the sub-nanogram range (nanochemistry). The HSARNs allow labeling increasing amounts of different chemical forms of toxicological or pharmacological interest, with the possibility to obtain dose vs. effect relationships on both cell cultures and laboratory animals. In nuclear medicine, “very high” AS - in No Carrier Added radiopharmaceuticals - are normally required to avoid undesirable effects due to high chemical concentration of labeled species. Some labeled species are sparingly soluble in body fluids, organs and barrier membranes; some others present toxic or adverse effects onto humans; a low AS(NCA) means a high molar concentration and could interfere into normal human metabolism, by inducing undesired pharmacological effects. High-resolution HPGe c-spectrometry and b-spectrometry by liquid scintillation counting allow determination of radionuclidic and radiochemical purities of the tracer and determination of radiochemical yield of processing procedures. Chemical purity determination is carried out by a range of analytical and radioanalytical techniques. Radionuclide production for biomedical applications has been brought up in the years, at LASA, particularly in co-operation with JRC-Ispra of EC and LENA-Pavi

Copper-64 production studies with natural zinc targets at deuteron energy up to 19 MeV and proton energy from 141 down to 31 MeV

High specific activity no-carrier-added 64Cu is a \u3b2-/\u3b2+ emitting radionuclide of increasing interest for PET imaging, as well as systemic and targeted radioimmunotherapy of tumors. Its peculiarity of intense Auger emitter is still under investigation. The cross-sections for prodn. of 64Cu from Zn target of natural isotopic compn. were measured in the deuteron energy range from threshold up to 19 MeV and proton energy range from 141 down to 31 MeV. The stacked-foil technique was used at both K = 38 cyclotron of JRC-Ispra of CEC, Italy and 160 MeV intersection point of NIR proton-LINAC in Troitsk, Russia. Several Ga, Zn, Cu, Ni, Co, V, Fe and Mn radionuclides were detected in Zn targets at the EOB. Optimized irradn. conditions are reported as a function of deuteron energy and energy loss into the Zn target, as well as target irradn. time and cooling time after radiochem. The activity of n.c.a. 64Cu was measured through its only y emission of 1346 keV (i.e., 0.473 intensity) both by instrumental and radiochem. methods, due to the non-specificity of annihilation radiation at 511 keV. To this last purpose, it was necessary to carry out a selective radiochem. sepn. of Ga(III) radionuclides by liq./liq. extn. from the bulk of irradiated Zn targets and other spallation products, which remained in the 7 M HCl aq. phase. Anion exchange chromatog. tests had been carried out to sep. the 60Cu from all others radionuclides in n.c.a. form. Theor. calcns. of cross-sections were performed with codes EMPIRE II and PENELOPE for deuteron reactions and CEF model and HMS-ALICE hybrid model for proton reactions. The theor. results are presented and compared with the exptl. values