1,721,250 research outputs found
The AEgIS experiment at CERN for the measurement of antihydrogen gravity acceleration
No full textThe Antihydrogen Experiment: Gravity, Interferometry, Spectroscopy (AEgIS) experiment
is conducted by an international collaboration based at CERN whose aim is to
perform the first direct measurement of the gravitational acceleration of antihydrogen
in the local field of the Earth, with Δg/g = 1% precision as a first achievement. The
idea is to produce cold (100 mK) antihydrogen ( ¯H) through a pulsed charge exchange
reaction by overlapping clouds of antiprotons, from the Antiproton Decelerator (AD)
and positronium atoms inside a Penning trap. The antihydrogen has to be produced in
an excited Rydberg state to be subsequently accelerated to form a beam. The deflection
of the antihydrogen beam can then be measured by using a moir´e deflectometer coupled
to a position sensitive detector to register the impact point of the anti-atoms through
the vertex reconstruction of their annihilation products. After being approved in late
2008, AEgIS started taking data in a commissioning phase in 2012. This paper presents
an outline of the experiment with a brief overview of its physics motivation and of the
state-of-the-art of the g measurement on antimatter. Particular attention is given to the
current status of the emulsion-based position detector needed to measure the ¯H sag in
AEgIS
Biological Effects of Accelerated Protons
No full textRadiobiological studies with proton beams started in the first half of the last century, when the scientific community could profit of
the Lawrence idea to accelerate protons. It became soon clear that such a radiation could be favourably used in clinical
applications. Since then, the biological effects of protons have been deeply investigated, in a wide energy range and several
biological end-points have been studied. Nowadays a partially overlapping research field is expanding aiming at radioprotection of
astronauts, a major concern because long-term manned space missions are foreseen.
In the present work the leading results of the most recent published data on proton radiobiology are reviewed
Solid state nuclear track detectors in hadrontherapy and radiation protection in space
No full textThe recent widespread of carbon therapy for cancer treatment and the long duration manned exploration planned by NASA require the knowledge of nuclear data both for assessing the correct dose distribution in the target volume and surrounding healthy tissue (radiation-therapy), and for a better knowledge of the mixed radiation field to which astronauts will be exposed (radiation protection in Space). Nuclear fragmentation taking place in traversed material, even human body itself, is indeed responsible for a beam quality change whose biological effects have to be evaluated. Solid State Nuclear Track Detectors (SSNTD) provide accurate measurements of fluence and fragmentation of heavy ions needed for hadrontherapy and Space radiation-protection purposes
Alternative routes for 64Cu production using an 18 MeV medical cyclotron in view of theranostic applications.
No full textRadiometals play a fundamental role in the development of personalized nuclear medicine. In particular, copper radioisotopes are attracting increasing interest since they offer a varying range of decay modes and half-lives and can be used for imaging (60Cu, 61Cu, 62Cu and 64Cu) and targeted radionuclide therapy (64Cu and 67Cu), providing two of the most promising true theranostic pairs, namely 61Cu/67Cu and 64Cu/67Cu. Currently, the most widely used in clinical applications is 64Cu, which has a unique decay scheme featuring β+-, β--decay and electron capture. These characteristics allow its exploitation in both diagnostic and therapeutic fields. However, although 64Cu has extensively been investigated in academic research and preclinical settings, it is still scarcely used in routine clinical practice due to its insufficient availability at an affordable price. In fact, the most commonly used production method involves proton irradiation of enriched 64Ni, which has a very low isotopic abundance and is therefore extremely expensive. In this paper, we report on the study of two alternative production routes, namely the 65Cu(p,pn)64Cu and 67Zn(p, α)64Cu reactions, which enable low and high 64Cu specific activities, respectively. To optimize the 64Cu production, while minimizing the mass of copper used as a target in the first case, or the co-production of other copper radioisotopes in the second case, an accurate knowledge of the production cross sections is of paramount importance. For this reason, the involved nuclear reaction cross sections were measured at the Bern medical cyclotron laboratory by irradiating enriched 65CuO and enriched 67ZnO targets. On the basis of the obtained results, the production yield and purity were calculated to assess the optimal irradiation conditions. Several production tests were performed to confirm these findings
Optimized production of 67Cu based on cross section measurements of 67Cu and 64Cu using an 18 MeV medical cyclotron.
Full text linkRadioNuclide Therapy (RNT) in nuclear medicine is a cancer treatment based on the administration of radioactive substances that specifically target cancer cells in the patient. These radiopharmaceuticals consist of tumor-targeting vectors labeled with β-, α, or Auger electron-emitting radionuclides. In this framework, 67Cu is receiving increasing interest as it provides β--particles accompanied by low-energy γ radiation. The latter allows to perform Single Photon Emission Tomography (SPECT) imaging for detecting the radiotracer distribution for an optimized treatment plan and follow-up. Furthermore, 67Cu could be used as therapeutic partner of the β+-emitters 61Cu and 64Cu, both currently under study for Positron Emission Tomography (PET) imaging, paving the way to the concept of theranostics. The major barrier to a wider use of 67Cu-based radiopharmaceutical is its lack of availability in quantities and qualities suitable for clinical applications. A possible but challenging solution is the proton irradiation of enriched 70Zn targets, using medical cyclotrons equipped with a solid target station. This route was investigated at the Bern medical cyclotron, where an 18 MeV cyclotron is in operation together with a solid target station and a 6-m-long beam transfer line. The cross section of the involved nuclear reactions were accurately measured to optimize the production yield and the radionuclidic purity. Several production tests were performed to confirm the obtained results
Cross-section measurement for an optimized 61Cu production at an 18 MeV medical cyclotron from natural Zn and enriched 64Zn solid targets.
No full textThe availability of novel medical radionuclides is a key point in the development of personalised nuclear medicine. In particular, copper radioisotopes are attracting considerable interest as they can be used to label various molecules of medical interest, such as proteins and peptides, and offer two of the most promising true theranostic pairs, namely 61Cu/67Cu and 64Cu/67Cu. Although 64Cu (t1/2 = 12.7006 h, β+: 17.6%, β-: 38.5%) is nowadays the most commonly used as a diagnostic radionuclide, 61Cu (t1/2 = 3.339 h, β+: 61%) features more favourable nuclear properties, such as a higher positron decay fraction and the absence of β- emissions. To date, the production of 61Cu has been carried out irradiating highly enriched 61Ni targets with a low energy proton beam. However, the use of the very expensive 61Ni targets requires an efficient recovery of the target material and makes this method quite inconvenient. Another promising production route is the proton irradiation of natural Zn or enriched 64Zn targets, exploiting the (p,α) nuclear reaction. Along this line, a research program is ongoing at the Bern medical cyclotron, equipped with an external beam transfer line and a solid target station. In this paper, we report on cross-section measurements of the 64Zn(p,α)61Cu nuclear reaction using natural Zn and enriched 64Zn material, which served as the basis to perform optimized 61Cu production tests with solid targets
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