Infrared system studies for the earth resource program Final report

Obtaining terrain surface temperatures from radiances measured in orbi

PoGOLite - A High Sensitivity Balloon-Borne Soft Gamma-ray Polarimeter

We describe a new balloon-borne instrument (PoGOLite) capable of detecting 10% polarisation from 200mCrab point-like sources between 25 and 80keV in one 6 hour flight. Polarisation measurements in the soft gamma-ray band are expected to provide a powerful probe into high-energy emission mechanisms as well as the distribution of magnetic fields, radiation fields and interstellar matter. At present, only exploratory polarisation measurements have been carried out in the soft gamma-ray band. Reduction of the large background produced by cosmic-ray particles has been the biggest challenge. PoGOLite uses Compton scattering and photo-absorption in an array of 217 well-type phoswich detector cells made of plastic and BGO scintillators surrounded by a BGO anticoincidence shield and a thick polyethylene neutron shield. The narrow FOV (1.25msr) obtained with well-type phoswich detector technology and the use of thick background shields enhance the detected S/N ratio. Event selections based on recorded phototube waveforms and Compton kinematics reduce the background to that expected for a 40-100mCrab source between 25 and 50keV. A 6 hour observation on the Crab will differentiate between the Polar Cap/Slot Gap, Outer Gap, and Caustic models with greater than 5 sigma; and also cleanly identify the Compton reflection component in the Cygnus X-1 hard state. The first flight is planned for 2010 and long-duration flights from Sweden to Northern Canada are foreseen thereafter.Comment: 11 pages, 11 figures, 2 table

Development of a positron emission tomograph for “in-vivo” dosimetry in hadrontherapy

This thesis is related to the DoPET project, which aims to evaluate the feasibility of a dedicated Positron Emission Tomograph (PET) for measuring, monitoring, and verifying the radiation dose that is being delivered to the patient during hadrontherapy. Radiation therapy with protons and heavier ions is becoming a more common treatment option, with many new centers under construction or at planning stage worldwide. The main physical advantage of these new treatment modalities is the high selectivity in the dose delivery: very little dose is deposited in healthy tissues beyond the particles’ range. However, in clinical practice the beam path in the patient is not exactly known. This affects the quality of the treatment planning, and may compromise the translation of the physical advantage into a clinical benefit. The use of a PET system immediately after the therapeutical irradiation (“in-beam”) for in-vivo imaging of the tissue + activation produced by nuclear reactions of the ion beam with the target, could help to have a better control of the treatment delivery. The DoPET project, based on an Italian INFN collaboration, aims to explore one possible approach to the hadron-driven PET technique, through the development of a dedicated device. Such goal was reached through the validation of a PET prototype with proton irradiations on plastic phantoms at the CATANA proton therapy facility (LNS-INFN, Catania, Italy) and with carbon irradiations on plastic phantoms at the GSI synchrotron (Darmstadt, Germany). A preliminary comparison with an existing in-beam PET device was also performed. The candidate was involved with all aspects of this project, specifically the Monte Carlo simulations of the physical processes at the basis of phantom activation, the measurements for the characterization of the DoPET detector, the improvement of the image reconstruction algorithm, and the extensive measurements in plastic phantoms. The system and the methods described in this thesis have to be considered as a proof of principle, and the promising results justify a larger effort for the construction of a clinical system

CASTER: a scintillator-based black hole finder probe

The primary scientific mission of the Black Hole Finder Probe (BHFP), part of the NASA Beyond Einstein program, is to survey the local Universe for black holes over a wide range of mass and accretion rate. One approach to such a survey is a hard X-ray coded-aperture imaging mission operating in the 10-600 keV energy band, a spectral range that is considered to be especially useful in the detection of black hole sources. The development of new inorganic scintillator materials provides improved performance (for example, with regards to energy resolution and timing) that is well suited to the BHFP science requirements. Detection planes formed with these materials coupled with a new generation of readout devices represent a major advancement in the performance capabilities of scintillator-based gamma cameras. Here, we discuss the Coded Aperture Survey Telescope for Energetic Radiation (CASTER), a concept that represents a BHFP based on the use of the latest scintillator technology

Muons tomography applied to geosciences and volcanology

Imaging the inner part of large geological targets is an important issue in geosciences with various applications. Dif- ferent approaches already exist (e.g. gravimetry, electrical tomography) that give access to a wide range of informations but with identified limitations or drawbacks (e.g. intrinsic ambiguity of the inverse problem, time consuming deployment of sensors over large distances). Here we present an alternative and complementary tomography method based on the measurement of the cosmic muons flux attenuation through the geological structures. We detail the basics of this muon tomography with a special emphasis on the photo-active detectors.Comment: Invited talk at the 6th conference on New Developments In Photodetection (NDIP'11), Lyon-France, July 4-8, 2011; Nuclear Instruments and Methods in Physics Research Section A, 201