A new branch of recent laser spectroscopy is given by Optical Magnetometry, where the sensor is an atomic sample interacting with laser light in such a way that it becomes extremely sensitive to the magnitude of the local magnetic field. This technique has been applied from geomagnetism to very low – level field ranges, being able to measure and track tiny signals, as for example in NMR, MRI, relaxometry, magnetocardiography, magnetoencephalography. In this paper, as a result of the collaboration with a group of the University College, London, a brief survey of a possible application of an optical magnetometer to Magnetic Induction Tomography will be given. MIT is based on the excitation of eddy currents in the object of interest, and in the detection of the weak magnetic field generated by them. One of the main problem in this kind of experiment is the exact reproduction of the shape of the object. We will present a post – analysis algorithm, as requested by our collaborators, allowing for a better performance in the pattern recognition.
We present the results of an edge detection algorithm applied on Electromagnetic Induction Imaging provided by an Atomic radio-frequency Magnetometer operating in an unshielded environment and at room temperature. Atomic Magnetometers have been already used for Imaging Techniques in the last few years, but the image reconstruction and the object pattern recognition lacks nowadays in terms of quality: the effect of scattering of e.m. signals at low-frequency provides blurred images, and does not allow for a clean ray – optics response, as in the case of X rays. Our algorithm, based on solved Gaussian Noise Recognition, demonstrates excellent spatial resolution achieved despite low Signal-to-Noise-Ratio.
The CALorimetric Electron Telescope (CALET) mission is proposed for a long exposure observation of high energy cosmic rays and gamma radiation, taking advantage of the JEM-EF facility on the International Space Station. The instrument is optimized for the search of nearby sources of acceleration of cosmic ray electrons in the TeV energy range. Its large collection power also allows for precision studies of the elemental composition of VHE nuclei and of their spectral features. The charge identification of the incoming particle is performed by a double-layered array of pixelated silicon sensors, covering a seamless sensitive area of the order of 1 m 2 . The conceptual design of the array and its front-end electronics are presented.
The CALorimetric Electron Telescope, CALET, is a new Space Observatory being developed for the Japanese Experiment Module Exposed Facility, JEM-EF, of the International Space Station. Major scientific objectives are to search for nearby cosmic ray sources and dark matter by carrying out a precise measurement of the electron spectrum from 10's of GeV - 10 TeV and of gamma rays in the range 20 MeV - several TeV. CALET has a unique capability to observe electrons and gamma-rays over 1 TeV, with a hadron rejection power better than 105 and an energy resolution of a few % beyond 100 GeV. Moreover, CALET will follow PAMELA, GLAST and other experiments and can both extend and refine the observations made by those missions. The main instrument, to be described, consists of an imaging calorimeter combined with a total absorption calorimeter. With auxiliary detectors, the CALET Observatory will also monitor solar activity and study gamma-ray bursts. The phase A/B study is underway for a proposed 2013 launch on the H-II Transfer Vehicle (HTV) for 3- 5 years of observation on JEM-EF.
We are developing the CALorimetric Electron Telescope, CALET, mission for the Japanese Experiment Module Exposed Facility, JEM-EF, of the International Space Station. Major scientific objectives are to search for the nearby cosmic ray sources and dark matter by carrying out a precise measurement of the electrons in 1 GeV - 20 TeV and gamma rays in 20 MeV - several 10 TeV. CALET has a unique capability to observe electrons and gamma rays over 1 TeV since the hadron rejection power can be larger than 105 and the energy resolution better than a few % over 100 GeV. The detector consists of an imaging calorimeter with scintillating fibers and tungsten plates and a total absorption calorimeter with BGO scintillators. CALET has also a capability to measure cosmic ray H, He and heavy ionsi up to 1000 TeV. It also will have a function to monitor solar activity and gamma ray transients. The phase A study has started on a schedule of launch in 2013 by H-II Transfer Vehicle (HTV) for 5 year observation.
We are developing the CALorimetric Electron Telescope, CALET, mission for the Japanese Experiment Module Exposed Facility, JEM-EF, of the International Space Station. Major scientific objectives are to search for the nearby cosmic ray sources and dark matter by carrying out a precise measurement of the electrons in 1 GeV - 20 TeV and gamma rays in 20 MeV - several 10 TeV. CALET has a unique capability to observe electrons and gamma rays over 1 TeV since the hadron rejection power can be larger than 105 and the energy resolution better than a few % over 100 GeV. The detector consists of an imaging calorimeter with scintillating fibers and tungsten plates and a total absorption calorimeter with BGO scintillators. CALET has also a capability to measure cosmic ray H, He and heavy ions up to 1000 TeV. It also will have a function to monitor solar activity and gamma ray transients. The phase A study has started on a schedule of launch in 2013 by H-II Transfer Vehicle (HTV) for 5 year observation.
Space-based and balloon-borne experiments, designed for direct measurements of the elemental composition and energy spectra of charged cosmic rays, require an unambiguous identification of the incoming particle. This task can be carried out via an accurate determination of the charge of the primary nucleus by dE/dx measurements with pixelated silicon detectors. At energies close to the knee (∼3–4×1015eV), the low values of the fluxes require large sensitive areas of a few m2. A prototype silicon detector with 64 pads (pixels of 1cm2 area) was developed on a 6″ wafer as a building block for a large area silicon array. Results on the characterization and performance of the detector are presented.
The CALorimetric Electron Telescope, CALET, mission is proposed for the Japanese Experiment Module Exposed Facility, JEM-EF, of the International Space Station. The mission goal is to reveal the high-energy phenomena in the universe by carrying out a precise measurement of the electrons in 1 GeV-10 TeV and the gamma-rays in 20 MeV-several TeV. The instrument will be composed of an imaging calorimeter of scintillating fibers and a total absorption calorimeter of BGO. The total thickness of absorber is 36 r.1 for electromagnetic particles and 1.6 m.f.p for protons. Total weight of the payload is nearly 2,500 kg, and the effective geometrical factor for the electrons could be larger than 0.5 similar to 1 m(2) sr. The CALET has a unique capability to measure the electrons and the gamma-rays over 1 TeV since the hadron rejection power might be 10 6 and the energy resolution of electromagnetic particles better than a few % over 100 GeV. Therefore, it is promising to detect the change of energy spectra and the gamma-ray line expected from candidates of the dark matter. We are expecting to launch the CALET around 2012 by the Japanese H-II Transfer Vehicle, HTV, and to observe for three years.
A new low-noise, low-power, front-end chip with a dynamic range larger than 10 4 was designed for operation on space-based or balloon-borne experiments. Its performance were optimized with negative polarity signals for the readout of Multi-Anode Photomultipliers (MAPMT). A suitable set of operation parameters were also determined for the readout of Hybrid Photo Diodes (positive polarity). The chip performances were tested for both polarities with two different test boards implementing 16-bit digitization. Test results are reported.
CREAM (Cosmic Ray Energetics And Mass) is a multi-flight balloon mission designed to collect direct data on the elemental composition and individual energy spectra of cosmic rays. Two instrument suites have been built to be flown alternately on a yearly base. The tungsten/Sci-Fi imaging calorimeter for the second flight, scheduled for December 2005, was calibrated with electron and proton beams at CERN. A calibration procedure based on the study of the longitudinal shower profile is described and preliminary results of the beam test are presented.
Cosmic Ray Energetics And Mass (CREAM) is a balloon-borne experiment designed to perform direct measurements of cosmic ray composition over the elemental range from proton to iron to the supernova energy scale of 1015eV in a series of balloon flights using the new Ultra Long Duration Balloon (ULDB) capability under development by NASA. The first flight of CREAM will take place at the end of 2004 from Antarctica. The instrument includes a sampling tungsten/scintillating fiber calorimeter preceded by a graphite target with scintillating fiber hodoscopes, a pixelated silicon charge detector, a transition radiation detector and a segmented timing-based particle-charge detector. The thin ionization calorimeter has been designed to operate in the range of energies from a few hundred GeV to 1PeV providing imaging capability in the reconstruction of the showers originating from the interaction of primary nuclei in the carbon target. A twin calorimeter for the second CREAM payload has been built and tested at CERN. Its construction technique and preliminary test results are presented.
CREAM (Cosmic Ray Energetics And Mass) is a balloon-borne experiment being prepared for the first flight which is scheduled for the end of 2004 from Antarctica. It is designed to perform direct measurements of cosmic ray composition over the elemental range from proton to iron to the supernova energy scale of 10(15) eV in a series of balloon flights using the new Ultra Long Duration Balloon (ULDB) capability under development by NASA. The instrument includes a sampling tungsten/ scintillating fiber calorimeter preceded by a graphite target with scintillating fiber hodoscopes, a pixelated silicon charge detector, a transition radiation detector and a segmented timing-based particle-charge detector. The hodoscope system provides track reconstruction capability by means of 4 orthogonal layers of fibers (S0,S1) on top of the carbon target and 2 additional layers (S2) located in between the upper and lower target sections. Its construction technique and beam test results are presented.
CREAM (Cosmic Ray Energetics And Mass) is an experiment under construction for a direct measurement of high energy cosmic rays (1012 to > 5 · 1014 eV) over the elemental range from proton to iron. The first flight of CREAM is intended to demonstrate the new Ultra Long Duration Balloon (ULDB) capability under development by NASA. A prototype of a tungsten-SciFi imaging calorimeter designed for CREAM has been tested at CERN with electron beam energies ranging from 5 to 100 GeV. Although the calorimeter module is optimized for cosmic-ray spectral measurements in the multi-TeV region, the response of its electromagnetic section to low energy electrons has been studied with this dedicated prototype. Results show good agreement with the expected behaviour in terms of linearity and energy resolution.
High granularity calorimeters with shower imaging capabilities require dedicated front-end electronics. The ICON_4CH and VA4_PMT chip-set is suitable for very high dynamic range systems with strict noise requirements. The ICON-4CH is a 4 channel input, 12 channel output ASIC designed for use in a multi-anode photomultiplier system with very large dynamic range and low-noise requirements. Each of the four input signals to the ASIC is split equally into three branches by a current conveyor. Each of the three branches is scaled differently: 1:1, 1:8 and 1:80. The signal is read out by a 12 channel low noise / low power high dynamic range charge sensitive preamplifiershaper circuit (VA4-PMT chip), with simultaneous sampleand-hold, multiplexed analog read-out, calibration facilities. Tests performed in our lab with a PMT are reported in terms of linearity, dynamic range and cross-talk of the system.
A low-noise CCD coupled to a structured CsI(Tl) scintillator via a fiber optic plate was operated as X-ray detector for digital mammography. The imaging capabilities of the device were measured in terms both of spatial resolution (MTF) and of noise properties (DQE, NPS). The detector was characterized using a standard mammographic tube with and without the coupling to a pair of anti-scatter projective grids. Breast phantom images were collected and compared to a MonteCarlo simulation of the apparatus. Contrast enhancement was achieved by using the anti-scatter grids.
A new technique for digital mammography based on the use of a collimator and an anti-scatter grid coupled with a mosaic detector has been studied with a Monte Carlo program. The simulation, with a low-energy spectrum X-ray beam and a breast phantom, provides a quantitative assessment of the capability of the method to reduce the physical background of the image due to scattering in the body, without introducing image artifacts. With minor modifications to the existing X-ray facilities, the method could also be applied to area detectors. To verify the results of the simulation, an experimental setup based on a CCD camera coupled via a fiber optic plate to a CsI(Tl) scintillator is under test.