172 research outputs found
Nuclear Emulsion Film Detectors for Proton Radiography: Design and Test of the First Prototype
Proton therapy is nowadays becoming a wide spread clinical practice in cancer
therapy and sophisticated treatment planning systems are routinely used to
exploit at best the ballistic properties of charged particles. The information
on the quality of the beams and the range of the protons is a key issue for the
optimization of the treatment. For this purpose, proton radiography can be used
in proton therapy to obtain direct information on the range of the protons, on
the average density of the tissues for treatment planning optimization and to
perform imaging with negligible dose to the patient. We propose an innovative
method based on nuclear emulsion film detectors for proton radiography, a
technique in which images are obtained by measuring the position and the
residual range of protons passing through the patient's body. Nuclear emulsion
films interleaved with tissue equivalent absorbers can be fruitfully used to
reconstruct proton tracks with very high precision. The first prototype of a
nuclear emulsion based detector has been conceived, constructed and tested with
a therapeutic proton beam at PSI. The scanning of the emulsions has been
performed at LHEP in Bern, where a fully automated microscopic scanning
technology has been developed for the OPERA experiment on neutrino
oscillations. After track reconstruction, the first promising experimental
results have been obtained by imaging a simple phantom made of PMMA with a step
of 1 cm. A second phantom with five 5 x 5 mm^2 section aluminum rods located at
different distances and embedded in a PMMA structure has been also imaged.
Further investigations are in progress to improve the resolution and to image
more sophisticated phantoms.Comment: Presented at the 11th ICATPP Conference on Astroparticle, Particle,
Space Physics, Detectors and Medical Physics Applications, Como (Italy),
October 200
A novel experimental approach to characterize neutron fields at high- and low-energy particle accelerators.
The characterization of particle accelerator induced neutron fields is challenging but fundamental for research and industrial activities, including radiation protection, neutron metrology, developments of neutron detectors for nuclear and high-energy physics, decommissioning of nuclear facilities, and studies of neutron damage on materials and electronic components. This work reports on the study of a novel approach to the experimental characterization of neutron spectra at two complex accelerator environments, namely the CERF, a high-energy mixed reference field at CERN in Geneva, and the Bern medical cyclotron laboratory, a facility used for multi-disciplinary research activities, and for commercial radioisotope production for nuclear medicine. Measurements were performed through an innovative active neutron spectrometer called DIAMON, a device developed to provide in real time neutron energy spectra without the need of guess distributions. The intercomparison of DIAMON measurements with reference data, Monte Carlo simulations, and with the well-established neutron monitor Berthold LB 6411, has been found to be highly satisfactory in all conditions. It was demonstrated that DIAMON is an almost unique device able to characterize neutron fields induced by hadrons at 120 GeV/c as well as by protons at 18 MeV colliding with different materials. The accurate measurement of neutron spectra at medical cyclotrons during routine radionuclide production for nuclear medicine applications is of paramount importance for the facility decommissioning. The findings of this work are the basis for establishing a methodology for producing controlled proton-induced neutron beams with medical cyclotrons
Methodology for measuring photonuclear reaction cross sections with an electron accelerator based on Bayesian analysis
Accurate measurements of photonuclear reaction cross sections are crucial for
a number of applications, including radiation shielding design, absorbed dose
calculations, reactor physics and engineering, nuclear safeguard and
inspection, astrophysics, and nuclear medicine. Primarily motivated by the
study of the production of selected radionuclides with high-energy photon beams
(mainly 225Ac, 47Sc, and 67Cu), we have established a methodology for the
measurement of photonuclear reaction cross sections with the microtron
accelerator available at the Swiss Federal Institute of Metrology (METAS). The
proposed methodology is based on the measurement of the produced activity with
a High Purity Germanium (HPGe) spectrometer and on the knowledge of the photon
fluence spectrum through Monte Carlo simulations. The data analysis is
performed by applying a Bayesian fitting procedure to the experimental data and
by assuming a functional trend of the cross section, in our case a Breit-Wigner
function. We validated the entire methodology by measuring a well-established
photonuclear cross section, namely the 197Au({\gamma},n)196Au reaction. The
results are consistent with those reported in the literature
SMAUG v1.0 – a user-friendly muon simulator for the imaging of geological objects in 3-D
Knowledge about muon tomography has spread in recent years in the geoscientific community and several collaborations between geologists and physicists have been founded. As the data analysis is still mostly done by particle physicists, much of the know-how is concentrated in particle physics and specialised geophysics institutes. SMAUG (Sim- ulation for Muons and their Applications UnderGround), a toolbox consisting of several modules that cover the various aspects of data analysis in a muon tomographic experiment, aims at providing access to a structured data analysis frame- work. The goal of this contribution is to make muon tomog- raphy more accessible to a broader geoscientific audience. In this study, we show how a comprehensive geophysical model can be built from basic physics equations. The emerging un- certainties are dealt with by a probabilistic formulation of the inverse problem, which is finally solved by a Monte Carlo Markov chain algorithm. Finally, we benchmark the SMAUG results against those of a recent study, which, however, have been established with an approach that is not easily accessi- ble to the geoscientific community. We show that they reach identical results with the same level of accuracy and preci- sion
Accelerator and detector physics at the Bern medical cyclotron and its beam transport line.
The cyclotron laboratory for radioisotope production and multi-disciplinary research at the Bern University Hospital (Inselspital) is based on an 18-MeV proton accelerator, equipped with a specifically conceived 6-m long external beam line, ending in a separate bunker. This facility allows performing daily positron emission tomography (PET) radioisotope production and research activities running in parallel. Some of the latest developments on accelerator and detector physics are reported. They encompass novel detectors for beam monitoring and studies of low current beams
Particle tracking at cryogenic temperatures: the Fast Annihilation Cryogenic Tracking (FACT) detector for the AEgIS antimatter gravity experiment
The AEgIS experiment is an interdisciplinary collaboration between atomic, plasma and particle physicists, with the scientific goal of performing the first precision measurement of the Earth's gravitational acceleration on antimatter. The principle of the experiment is as follows: cold antihydrogen atoms are synthesized in a Penning-Malmberg trap and are Stark accelerated towards a moiré deflectometer, the classical counterpart of an atom interferometer, and annihilate on a position sensitive detector. Crucial to the success of the experiment is an antihydrogen detector that will be used to demonstrate the production of antihydrogen and also to measure the temperature of the anti-atoms and the creation of a beam. The operating requirements for the detector are very challenging: it must operate at close to 4 K inside a 1 T solenoid magnetic field and identify the annihilation of the antihydrogen atoms that are produced during the 1 μs period of antihydrogen production. Our solution—called the FACT detector—is based on a novel multi-layer scintillating fiber tracker with SiPM readout and off the shelf FPGA based readout system. This talk will present the design of the FACT detector and detail the operation of the detector in the context of the AEgIS experiment
Positron bunching and electrostatic transport system for the production and emission of dense positronium clouds into vacuum
We describe a system designed to re-bunch positron pulses delivered by an accumulator supplied by a positron source and a Surko-trap. Positron pulses from the accumulator are magnetically guided in a 0.085 T field and are injected into a region free of magnetic fields through a μ -metal field terminator. Here positrons are temporally compressed, electrostatically guided and accelerated towards a porous silicon target for the production and emission of positronium into vacuum. Positrons are focused in a spot of less than 4 mm FWTM in bunches of ∼8 ns FWHM. Emission of positronium into the vacuum is shown by single shot positron annihilation lifetime spectroscopy
First Direct Observation of Collider Neutrinos with FASER at the LHC
We report the first direct observation of neutrino interactions at a particle
collider experiment. Neutrino candidate events are identified in a 13.6 TeV
center-of-mass energy collision data set of 35.4 fb using the
active electronic components of the FASER detector at the Large Hadron
Collider. The candidates are required to have a track propagating through the
entire length of the FASER detector and be consistent with a muon neutrino
charged-current interaction. We infer neutrino interactions
with a significance of 16 standard deviations above the background-only
hypothesis. These events are consistent with the characteristics expected from
neutrino interactions in terms of secondary particle production and spatial
distribution, and they imply the observation of both neutrinos and
anti-neutrinos with an incident neutrino energy of significantly above 200 GeV.Comment: Submitted to PRL on March 24 202
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