Search results for "RADIOCHEMISTRY"

Determination of nuclear spins of short-lived Rb and Cs isotopes by β radiation detected optical pumping

1978

Improvement of the LET sensitivity in ESR dosimetry for -photons and thermal neutrons through gadolinium addition

2007

Abstract We investigated the ESR response of new materials, alanine and ammonium tartrate to which gadolinium was added. The addition of gadolinium enhances sensitivity for Co 60 γ -photons because of its high atomic number ( Z = 64 ) and an enhancement of sensitivity for thermal neutrons because of its high thermal neutron cross section and high linear energy transfer (LET) secondary particles produced after the reaction with neutrons. In particular, in this paper we analyzed the microwave power saturation properties of dosimeters of alanine and ammonium tartrate with or without gadolinium exposed to different LET beams. The power saturation trends of dosimeters exposed to photons and to t…

Search for the radioactivity of 180mTa using an underground HPGe sandwich spectrometer

2009

Abstract The radioactivity of 180m Ta has never been detected. The present attempt to detect it was carried out using a newly developed HPGe sandwich spectrometer installed 500 m water equivalent underground in the HADES laboratory. The sample consisted of 6 discs of tantalum of natural isotopic composition with a total mass of 1500 g and a total mass for 180 Ta of 180 mg. The sample was measured for 68 days and the resulting lower bound for the half-life of 180m Ta was 2.0×10 16  y, which is a factor of 2.8 higher than the previous highest value.

Production of Exotic Nuclei via MNT Reactions Using Gas Cells

2020

The use of multi-nucleon transfer (MNT) reactions to produce neutron-rich nuclei in the heavy region has received an increased attention in the last decade. The feasibility of employing such reactions at the FRS Ion Catcher facility at GSI and the IGISOL facility at JYFL is studied using a combination of theoretical calculations and experiment simulations. The reactions are computed within a Langevin-type model, and the Geant program is used to simulate the transport of the resulting products within the experimental setups of the above-mentioned facilities. The angular distribution of ion release, possible target choices and target-to-beam-dump distances are discussed. peerReviewed

Measurement of radionuclide activities induced in target components of an IBA CYCLONE 18/9 by gamma-ray spectrometry with HPGe and LaBr3: Ce detector…

2014

Cyclotrons are used worldwide to produce radiopharmaceuticals by proton irradiation of a suitable target. The intense secondary neutron beam generated by proton interactions with the target induce high radionuclide activities in the target assembly parts that may result in an exposure to high dose levels of the operators during maintenance. The main goal of this work is to evaluate gamma-emitting radionuclide activities induced in Havar foils and titanium windows of a target assembly and carousel stripper forks of an IBA CYCLONE 18/9 cyclotron. The knowledge of radionuclide inventory for each component is required by many companies to assess risk for operators before waste handling and disp…

Trial for the long neutron counter TETRA using $^{96,97}$Rb radioactive sources

2019

International audience; The TETRA long neutron counter is operated at ALTO ISOL facility behind the PARRNe mass separator. TETRA has been proven to be a unique instrument for measurements of β-decay properties of short-lived neutron-rich nuclei having applications for the nuclear structure and/or astrophysical r-process calculations. A proper calibration of TETRA can allow validation of the experimental procedure used for determination of β-delayed one-neutron emission probabilities (P1n). It requires the use of a well-known β-neutron decaying radioactive source which can be only produced and measured on-line due to its short half-life. Thus, the present paper reports on measurements of P1n…

Titanate nanotubes as versatile nanovectors : radiosensitizers for the treatment of prostate cancer and nuclear imaging probes

2017

Currently, the systemic injections of drugs reach very weakly tumor sites and large doses are thus administered causing adverse side effects. The new implementations of nanoparticles in the medical field offer new strategies to vectorize an active substance in diseased cells. This work is focused on the prostate cancer, which is the second most frequently diagnosed cancer and the fifth leading cause of cancer death in men worldwide.Titanate nanotubes (TiONts) are synthetized by a hydrothermal process and have average dimensions of about 170 nm in length, 10 nm in outer diameter and also have an internal cavity of 4 nm in diameter. Their needle-shaped morphology allows them to be internalize…

H(II) centers in natural silica under repeated UV laser irradiations

2004

We investigated the kinetics of H(II) centers (=Ge'-H) in natural silica under repeated 266nm UV irradiations performed by a Nd:YAG pulsed laser. UV photons temporarily destroy these paramagnetic defects, their reduction being complete within 250 pulses. After re-irradiation, H(II) centers grow again, and the observed recovery kinetics depends on the irradiation dose; multiple 2000 pulses re-irradiations induce the same post-irradiation kinetics of H(II) centers after each exposure cycle. The analysis of these effects allows us to achieve a deeper understanding of the dynamics of the centers during and after laser irradiation.

Photoluminescence in gamma-irradiated alpha-quartz investigated by synchrotron radiation

2004

Abstract We report an experimental investigation of the photoluminescence, under excitation by synchrotron radiation within the absorption band at 7.6 eV , induced in γ-irradiated α-quartz. Two emissions centered at 4.9 and 2.7 eV are observed at low temperature: the former decreases above 40 K , whereas the second band exhibits an initial slight increase and its quenching is effective above 100 K . Furthermore, the decay kinetics of both emissions occur in a time scale of nanoseconds: at T=17.5 K we measured a lifetime τ∼1.0 ns for the photoluminescence at 4.9 eV and τ∼3.6 ns for that at 2.7 eV . These results give new insight on the optical properties associated with defects peculiar of c…

Determination of gold in two Egyptian gold ores using instrumental neutron activation analysis

2003

Abstract The applicability of thermal neutron activation analysis for the determination of gold and other elements in two Egyptian gold ores has been studied. Ten samples collected from El Sukari and Atud in the Eastern Desert-Egypt have been analyzed. The samples were properly prepared together with their standards and simultaneously irradiated in a neutron flux of the order 7×10 11  n/cm 2  s using the TRIGA research reactor at Mainz. Short-term (1 and 5 m) irradiation in the pneumatic system was also used for detection of the elements with shorter half-lives. After activation, the samples were subjected to γ -ray spectrometry using a high-purity germanium detection system and computerize…