Search

The proton charge distribution radius is a nuclear physics related observable. QED calculations involve its value. It depends on the Lamb shift and hyperfine splitting which experimentally measured, are considered tests of QED, involving the Rydberg and the fine structure constant. The CREMA collaboration measured the proton radius by using muonic hydrogen spectroscopy. Muon, which is 200 times heavier than the electron, orbits close to the nucleus offering a unique probe for the proton structure. They obtained a precise measurement of the proton radius but 5% smaller than the one from hydrogen spectroscopy and electron-proton scattering. This discrepancy, called "the proton radius puzzle" and it is still an unanswered problem. There is another proton observable, related to both the charge and magnetic distribution, called the Zemach radius. This is dependent on QED and is strictly related to the hyperfine splitting. Different methods for measuring the Zemach radius are not in agreement and so far, a precise estimation of this observable for muonic hydrogen doesn't exist. In this context, FAMU, aims to measure the hyperfine splitting of the muonic hydrogen in the ground state which allows a level of uncertainty better than 1%. This will result in the first precise measurement of the Zemach radius with muonic hydrogen spectroscopy. Adding an independent precise measurement of the Zemach radius in the current panorama should give a hint to the proton radius puzzle solution. Moreover, it will influence the nuclear structure theories of simple atoms and act as a precise test of QED. The physical processes behind these measurements are related to muonic atomic physics. In particular, the ability of the muonic hydrogen to transfer its muon to nearby heavy atoms when in a gaseous mixture. The rate of this transfer process was found to be energy dependent for some elements.

FLARES is an innovative project in the field of rare events searches, such as the search for the neutrinoless double beta decay. It aims at demonstrating the high potential of a technique that combines ultra-pure scintillating crystals with arrays of high performance silicon drift detectors, operated at about 120 K, to reach a 1% level energy resolution. The proposed technique will combine in a single device all the demanding features needed by an ideal experiment looking for rare events. The performance of a first production of matrices of silicon drift detectors as well as first measurements of the low temperature light yield of a selection of high purity scintillating crystals will be presented and discussed. © 2016 Elsevier B.V.

The XAFS beamline at Elettra Synchrotron in Trieste combines X-ray absorption spectroscopy and X-ray diffraction to provide chemically specific structural information of materials. It operates in the energy range 2.4-27 keV by using a silicon double reflection Bragg monochromator. The fluorescence measurement is performed in place of the absorption spectroscopy when the sample transparency is too low for transmission measurements or the element to study is too diluted in the sample. We report on the development and on the preliminary tests of a new prototype detector based on Silicon Drift Detectors technology and the SIRIO ultra low noise front-end ASIC. The new system will be able to reduce drastically the time needed to perform fluorescence measurements, while keeping a short dead time and maintaining an adequate energy resolution to perform spectroscopy. The custom-made silicon sensor and the electronics are designed specifically for the beamline requirements., Comment: Proceeding of the 6YRM 12th-14th Oct 2015 - L'Aquila (Italy). Accepted for publication on Journal of Physics: Conference Series

Consolidated techniques used for space-borne X-ray and gamma-ray instruments are based on the use of scintillators coupled to Silicon photo-detectors. This technology associated with modern very low noise read-out electronics allows the design of innovative architectures able to reduce drastically the system complexity and power consumption, also with a moderate-to-high number of channels. These detector architectures can be exploited in the design of space instrumentation for gamma-spectroscopy with the benefit of possible smart background rejection strategies. We describe a detector prototype with 3D imaging capabilities to be employed in future gamma-ray and particle space missions in the 0.002-100 MeV energy range. The instrument is based on a stack of scintillating bars read out by Silicon Drift Detectors (SDDs) at both ends. The spatial segmentation and the crystal double-side readout allow a 3D position reconstruction with ∼3 mm accuracy within the full active volume, using a 2D readout along the two external faces of the detector. Furthermore, one of the side of SDDs can be used simultaneously to detect X-rays in the 2-30 keV energy range. The characteristics of this instrument make it suitable in next generation gamma-ray and particle space missions for Earth or outer space observations, and it will be briefly illustrated.

The high precision measurement of the hyperfine splitting of the muonic-hydrogen atom ground state with pulsed and intense muon beam requires careful technological choices both in the construction of a gas target and of the detectors. In June 2014, the pressurized gas target of the FAMU experiment was exposed to the low energy pulsed muon beam at the RIKEN RAL muon facility. The objectives of the test were the characterization of the target, the hodoscope and the X-ray detectors. The apparatus consisted of a beam hodoscope and X-rays detectors made with high purity Germanium and Lanthanum Bromide crystals. In this paper the experimental setup is described and the results of the detector characterization are presented., Comment: 22 pages, 14 figures, published and open access on JINST

FLARES is a project for an innovative detector technology to be applied to rare event searches, and in particular to neutrinoless double beta decay experiments. Its novelty is the enhancement and optimization of the collection of the scintillation light emitted by ultra-pure crystals through the use of arrays of high performance silicon photodetectors cooled to 120 K. This would provide scintillation detectors with 1% level energy resolution, with the advantages of a technology offering relatively simple low cost mass scalability and powerful background reduction handles, as requested by future neutrinoless double beta decay experimental programs. The performances of a first production of matrices of Silicon Drift Detectors are presented and discussed in this paper.

A fast continuous sampling digitizer has been designed to acquire fast scintillating detector signal from cerium activated lantanum bromide (LaBr3(Ce)) scintillation crystal. These are foreseen in the FAMU experiment which is aimed at spectroscopic measurements of muonic hydrogen, possibly providing insights into the so-called proton radius puzzle. The board, named GSPS, is implemented as an FMC mezzanine which hosts two off-the-shelf sampling ADC used in interleaved timing architecture, achieving a 1 GS/s sampling rate (with a 12-bit nominal accuracy over the first Nyquist interval of frequencies, ranging from DC to 500 MHz). Interleaved technique allowed us to keep both lower production costs and simple acquisition system avoiding complex interface protocols like JESD204. The board will be described; the test setup and the used methodology to characterize the device will be explained; the achieved performances will be shown and discussed. In particular it will be pointed out how the two interleaved ADCs can be calibrated in order to get the best performance. The different contributions to both noise and distortion affecting the device will be analyzed applying general techniques for high-sampling-speed continuous ADCs. Lastly, future improvements will be introduced: in particular, the solutions we foresee to get a effective number of bits of about 10 over the whole first Nyquist interval will be enlightened.