The FAMU experiment: Towards the measurement of the hyperfine splitting of the muonic hydrogen

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

Sviluppo di un sistema di rivelazione per l'esperimento FAMU (fisica degli atomi muonici) basato su scintillatore LaBr3 con fotomoltiplicatore UQE e sistema spettrometrico DSP

In questa tesi si sono studiati e sviluppati i rivelatori di fotoni x per l’esperimento FAMU (Fisica degli Atomi Muonici gruppo 3 dell’INFN) che indaga sulla natura e la struttura del protone. I rivelatori sono stati assemblati e testati con elementi che rappresentano lo stato dell’arte nel campo dei rivelatori di radiazione (scintillatori LaBr3(Ce) e fotomoltiplicatori Hamamatsu™ Ultra Bi-Alcali). È stata anche studiata e sviluppata parte della catena di formatura del segnale. Questa è stata implementata su un chip FPGA dell’ALTERA™ con buoni risultati per quanto riguarda la qualità del filtro; le performance dell’FPGA non hanno consentito di raggiungere la velocità di 500MHz richiesta dall’esperimento costringendo l’implementazione ad una velocità massima di 320MHz

A 1 GS/s sampling digitizer designed with interleaved architecture (GSPS) for the LaBr3 detectors of the FAMU experiment

A fast continuous sampling digitizer has been designed to acquire fast scintillating detector signalfrom cerium activated lantanum bromide (LaBr3(Ce)) scintillation crystal. These are foreseenin 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 in-terleaved timing architecture, achieving a 1 GS/s sampling rate (with a 12-bit nominal accuracyover the first Nyquist interval of frequencies, ranging from DC to 500 MHz). Interleaved tech-nique allowed us to keep both lower production costs and simple acquisition system avoidingcomplex interface protocols like JESD204. The board will be described; the test setup and theused methodology to characterize the device will be explained; the achieved performances willbe shown and discussed. In particular it will be pointed out how the two interleaved ADCs can becalibrated in order to get the best performance. The different contributions to both noise and dis-tortion affecting the device will be analyzed applying general techniques for high-sampling-speedcontinuous ADCs. Lastly, future improvements will be introduced: in particular, the solutions weforesee to get a effective number of bits of about 10 over the whole first Nyquist interval will beenlightened

Comparison between a silicon PIN diode and a CsI(Tl) coupled to a silicon PIN diode for dosimetric purpose in radiology

The use of amorphous Si-PIN diodes showed interesting applications in detector research. Due to their properties and cost effective value, these devices can be used as small dosimeters for fast and real time dose evaluation. The responses of two different detectors to the measurement of X-ray total air KERMA are compared and presented, with the goal to get a dosimetric parameter directly during the X-ray patients exposure. A bare Si-PIN diode and a Si-PIN diode+CsI(Tl) scintillator were tested and compared to radiologic dosimeters. Both detector outputs were calibrated using a secondary reference standard (CAPINTEC PM 30 dosimeter), in order to analyze and discuss the dose and the energy dependence of the detectors in the range of radiologic interest (tube voltage: 40–140 kVp and additional filtration: 0 mm Al to 4 mm Al). The bare Si-PIN diode shows a very coherent response independently from the X-ray beam quality and from the additional filtration. The Si-PIN+CsI(Tl) detector, on the other hand, shows a high spread of the calibration curves as a function of the tube high voltage and the additional filtration. The presented results could be used to calibrate an image detector in dose

A programmable System-on-Chip based digital pulse processing for high resolution X-ray spectroscopy

none18noIt is described the global architecture of a digital pulse processing system for high resolution X-Ray spectroscopy based on single photon detection and photon energy measurement. The core of the system is implemented in a modern hybrid device (Xilinx Zynq) that integrates an FPGA fabric along with a dual core 32-bits processor (ARM Cortex). It is also described the adopted strategy to deal with high input photon rates while preserving a good energy resolution. The digital performance of the system is ultimate determined by few key functional blocks including two finite impulse response filters and an algorithmic state machine. It is presented a numerical procedure to optimize the digital filters according to different constrains and goals, and it is described the analysis of experimental data to obtain the necessary information for the optimization of the system.Cicuttin, Andres; Crespo, Maria Liz; Mannatunga, Kasun Sameera; Garcia, Victor Villaverde; Baldazzi, Giuseppe; Rignanese, Luigi Pio; Ahangarianabhari, Mahdi; Bertuccio, Giuseppe; Fabiani, Sergio; Rachevski, Alexander; Rashevskaya, Irina; Vacchi, Andrea; Zampa, Gianluigi; Zampa, Nicola; Bellutti, Pierluigi; Picciotto, Antonino; Piemonte, Claudio; Zorzi, NicolaCicuttin, Andres; Crespo, Maria Liz; Mannatunga, Kasun Sameera; Garcia, Victor Villaverde; Baldazzi, Giuseppe; Rignanese, Luigi Pio; Ahangarianabhari, Mahdi; Bertuccio, Giuseppe; Fabiani, Sergio; Rachevski, Alexander; Rashevskaya, Irina; Vacchi, Andrea; Zampa, Gianluigi; Zampa, Nicola; Bellutti, Pierluigi; Picciotto, Antonino; Piemonte, Claudio; Zorzi, Nicol