Since its commissioning in December 2017, the CERN-MEDICIS facility has been providing non-conventional radionuclides for research in nuclear medicine. Benefitting from decades of experience in the ...production of radioactive ion beams and in the mass separation process from the ISOLDE facility at CERN, MEDICIS quickly became a worldwide key player in the supply of novel medical isotopes dedicated to research in the fields of cancer imaging, diagnostics, and radiation therapy.
After a few years of operation, successful collections have been performed on a large panel of radionuclides such as 128Ba, 149,152,155Tb, 153Sm, 165,167Tm, 169Er, 175Yb, 191Pt, and 225,227Ac. Several milestones have been achieved on the output of the facility, such as the collection of 0.5 GBq of 175Yb, and a total separation efficiency higher than 50% reached for 167Tm in 2020. These collections led to notable recent in-vitro and preclinical results in targeted radionuclide therapy achieved with high molar activity 175Yb and 153Sm products.
Constant developments are ongoing, such as innovative target designs, molecular formation to improve the release of some specific isotopes, laser development in the dedicated MELISSA laboratory, study of new implantation foil materials, and post-collection radiochemistry.
The results of more than 280 different experiments aimed at exploring the main features and performances of a newly developed gamma imager, called iPIX, are summarized in this paper. iPIX is designed ...to quickly localize radioactive sources while estimating the ambient dose equivalent rate at the measurement point. It integrates a 1 mm thick CdTe detector directly bump-bonded to a Timepix chip, a tungsten coded-aperture mask, and a mini RGB camera. It also represents a major technological breakthrough in terms of lightness, compactness, usability, response sensitivity, and angular resolution. As an example of its key strengths, an super(241)Am source with a dose rate of only few nSv/h can be localized in less than one minute.
Previous work showed that enriched
6Li halide scintillation crystal is a good candidate for portable neutron-sensitive detectors. Photodiode readout is a good alternative to PMT in compact devices. ...These detectors are often required to work in presence of a strong gamma background. Therefore, great discrimination against gamma rays is crucial. Because of the high
Q-value of the
6Li(n,α)
3H reaction, the light yield of a neutron capture signal corresponds to 3–4
MeV gamma equivalent in spite of the quenching effect of heavily charged particles. As a result, energy discrimination is quite effective against gamma signals generated in thin crystals. However, direct gamma interactions inside the photodiode can create pulses whose amplitude is large enough to interfere with thermal neutron peak. This study shows an innovative design based on coincident readout to solve this problem. In this design, two photodiodes are attached on both sides of the LiI crystal. The output signal is only accepted when both photodiodes give out coincident output. The method is proved to effectively suppress background in the neutron window in a 420
mR/h
137Cs field down to the level of natural background.
The CLEO RICH detector Artuso, M.; Ayad, R.; Bukin, K. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2005, Letnik:
554, Številka:
1
Journal Article
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Odprti dostop
We describe the design, construction and performance of a Ring Imaging Cherenkov Detector (RICH) constructed to identify charged particles in the CLEO experiment. Cherenkov radiation occurs in LiF ...crystals, both planar and ones with a novel “sawtooth”-shaped exit surface. Photons in the wavelength interval 135–165
nm are detected using multi-wire chambers filled with a mixture of methane gas and triethylamine vapor. Excellent
π
/
K
separation is demonstrated.
Accurate determination of neutron dose equivalent requires knowledge of the neutron energy distribution. Existing neutron spectrometers, such as Bonner sphere sets, are typically bulky and require ...long acquisition times. Hence, a handheld or portable system that could perform area monitoring with acceptable accuracy would be of interest. Such a device will require a detector that is efficient, and possesses gamma-neutron discrimination capabilities. An organic scintillator that contains lithium, gadolinium, and boron, all three of which possess isotopes with large neutron capture cross-sections for highly exothermic reactions, has been recently developed by MSI/Photogenics. This combination of materials provides for the detection of fast neutrons by proton recoil which when used in conjunction with a slow neutron capture gate allows total energy information to be obtained. The system also responds to gamma-rays but n-gamma discrimination techniques allow it to be applied in mixed fields. Photogenics recently completed the full demonstration of a Lithium Gadolinium Borate (LGB) neutron spectrometer's performance under a Department of Homeland Security Domestic Nuclear Detection Office (DNDO) grant. A potential application suggested for this technology is in the identification of shielded fissile materials. A 2" times 2" (50.8 mm times 50.8 mm) sample of composite scintillator, consisting of lithium gadolinium borate crystals in a plastic scintillator matrix, produced by Photogenics has been tested for this purpose. The Tests consist of verifying the n-gamma discrimination and measurements of both capture and capture gated efficiencies using 252 Cf and Am-Li neutron sources of various activities under a variety of gamma shielding and neutron attenuation geometries. The results, for this small test sample, showed that in addition to its rudimentary spectroscopic capability, the Photogenics LGB detector has a overall neutron detection efficiency that is attractive for handheld applications.
Nuclear instruments such as alpha/beta contamination meter are frequently used in a compensated mode where the contribution of gamma radiation background is compensated by a guard detector. The ...signal of interest is then the subtraction of counting from both channels. In practice, the noise signal measured by the guard detector is not strictly equal to the noise contribution into the first detector due to anisotropic biases.
The random error (under Poisson assumption) is taken into account to build a hypothesis test. The system is also designed to minimize the systematic error but in some cases, this bias could not be completely removed. The measurement system then shows different behavior when the surrounding environment changes exhibiting inopportune false alarms.
A method allowing the false alarms to be suppressed is addressed in this study for compensated measurement. An improvement in terms of reliability has been proven.
Using data collected near the D{s}{*+}D{s}{-} peak production energy E_{cm}=4170 MeV by the CLEO-c detector, we study the decays of D{s}{+} mesons to two pseudoscalar mesons. We report on searches ...for the singly Cabibbo-suppressed D{s}{+} decay modes K{+}eta, K{+}eta', pi{+}K{S}{0}, K{+}pi{0}, and the isospin-forbidden decay mode D{s}{+}-->pi{+}pi{0}. We normalize with respect to the Cabibbo-favored D{s}{+} modes pi{+}eta, pi{+}eta', and K{+}K{S}{0}, and obtain ratios of branching fractions: B(D{s}{+}-->K{+}eta)/B(D{s}{+}-->pi{+}eta)=(8.9+/-1.5+/-0.4)%, B(D{s}{+}-->K{+}eta')/B(D{s}{+}-->pi{+}eta')=(4.2+/-1.3+/-0.3)%, B(D{s}{+}-->pi{+}K{S}{0})/B(D{s}{+}-->K{+}K{S}{0})=(8.2+/-0.9+/-0.2)%, B(D{s}{+}-->K{+}pi{0})/B(D{s}{+}-->K{+}K{S}{0})=(5.5+/-1.3+/-0.7)%, and B(D{s}{+}-->pi{+}pi{0})/B(D{s}{+}-->K{+}K{S}{0})<4.1% at 90% C.L., where the uncertainties are statistical and systematic, respectively.
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