Thermal analysis of the antineutrino 144Ce source calorimeter for the SOX experiment

The technical note describes the calorimeter which will be used to measure the activity of the antineutrino 144Ce source of the SOX experiment at the Gran Sasso Laboratories. The principle of the calorimeter is based on the measurement of both mass flow and temperature increase of the water circulating in the heat exchanger surrounding the source. The calorimeter is vacuum insulated in order to minimize the heat losses. The preliminary design and thermal Finite Element Analysis (FEA) are reported in the note

Borexino : geo-neutrino measurement at Gran Sasso, Italy

Geo-neutrinos, electron anti-neutrinos produced in beta-decays of naturally occurring radioactive isotopes in the Earth, are a unique direct probe of our planet's interior. After a brief introduction of the geo-neutrinos' properties and of the main aims of their study, we discuss the features of a detector which has recently provided breakthrough achievements in the field, Borexino, a massive, calorimetric liquid scintillator detector installed at the underground Gran Sasso Laboratory. With its unprecedented radiopurity levels achieved in the core of the detection medium, it is the only experiment in operation able to study in real time solar neutrino interactions in the challenging sub-MeV energy region. Its superior technical properties allowed Borexino also to provide a clean detection of terrestrial neutrinos. Therefore, the description of the characteristics of the detected geo-neutrino signal and of the corresponding geological implications are the main core of the discussion contained in this work

Research and Development for Near Detector Systems Towards Long Term Evolution of Ultra-precise Long-baseline Neutrino Experiments

With the discovery of non-zero value of $\theta_{13}$ mixing angle, the next generation of long-baseline neutrino (LBN) experiments offers the possibility of obtaining statistically significant samples of muon and electron neutrinos and anti-neutrinos with large oscillation effects. In this document we intend to highlight the importance of Near Detector facilities in LBN experiments to both constrain the systematic uncertainties affecting oscillation analyses but also to perform, thanks to their close location, measurements of broad benefit for LBN physics goals. A strong European contribution to these efforts is possible

A first update on mapping the human genetic architecture of COVID-19

peer reviewe

Positronium in the AEgIS experiment: study on its emission from nanochanneled samples and design of a new apparatus for Rydberg excitations

This experimental thesis has been done in the framework of AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy), an experiment installed at CERN, whose primary goal is the measurement of the Earth's gravitational acceleration on anti-hydrogen. The antiatoms will be produced by the charge exchange reaction, where a cloud of Ps in Rydberg states interacts with cooled trapped antiprotons. Since the charge exchange cross section depends on Ps velocity and quantum number, the velocity distribution of Ps emitted by a positron-positronium converter as well as its excitation in Rydberg states have to be studied and optimized. In this thesis Ps cooling and emission into vacuum from nanochannelled silicon targets was studied by performing Time of Flight measurements with a dedicated apparatus conceived to receive the slow positron beam as produced at the Trento laboratory or at the NEPOMUC facility at Munich. Measurements were done by varying the positron implantation energy, the sample temperature and the nanochannel dimensions, with the aim of finding the best parameters to increase Ps fraction having velocity lower than 5 10^4 m/s. Preliminary data were analyzed in order to extract the Ps velocity distribution and its average temperature. More, an original method for evaluating the permanence time of Ps inside the nanochannels before being emitted into vacuum, was described. A first rough evaluation based on the performed measurements is reported and this result will be useful to investigate the Ps cooling process and to synchronize the laser pulse for Ps excitation in the AEgIS experiment. In order to perform measurements of Ps excitation in Rydberg states, a new apparatus for bunching positron pulses, coming from the AEgIS positron line, was designed and built. COMSOL and SIMION softwares were used for designing a magnetic transport line and an electron optical line, which extracts positrons from the magnetic field and focus them on the nanochanneled Si sample. More, a buncher device, which spatio-temporally compresses the positron bunches, was built and a fast circuit for supplying the 25 buncher electrodes with a parabolic shaped potential was designed and tested. According to the simulations, at the target position the device will deliver positrons with an energy ranging from 6 to 9 keV, in bunches of 5 ns duration and a spot of 2.5 mm in diameter. By using this apparatus, first measurements for the optimization of Ps excitation in Rydberg states and studies on the Ps levels with and without magnetic field will be performed. At a later stage investigations of Ps spectroscopy or of Ps laser cooling with the same apparatus could be achievable for the first time

Positronium in the AEgIS experiment: study on its emission from nanochanneled samples and design of a new apparatus for Rydberg excitations

This experimental thesis has been done in the framework of AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy), an experiment installed at CERN, whose primary goal is the measurement of the Earth's gravitational acceleration on anti-hydrogen. The antiatoms will be produced by the charge exchange reaction, where a cloud of Ps in Rydberg states interacts with cooled trapped antiprotons. Since the charge exchange cross section depends on Ps velocity and quantum number, the velocity distribution of Ps emitted by a positron-positronium converter as well as its excitation in Rydberg states have to be studied and optimized. In this thesis Ps cooling and emission into vacuum from nanochannelled silicon targets was studied by performing Time of Flight measurements with a dedicated apparatus conceived to receive the slow positron beam as produced at the Trento laboratory or at the NEPOMUC facility at Munich. Measurements were done by varying the positron implantation energy, the sample temperature and the nanochannel dimensions, with the aim of finding the best parameters to increase Ps fraction having velocity lower than 5 10^4 m/s. Preliminary data were analyzed in order to extract the Ps velocity distribution and its average temperature. More, an original method for evaluating the permanence time of Ps inside the nanochannels before being emitted into vacuum, was described. A first rough evaluation based on the performed measurements is reported and this result will be useful to investigate the Ps cooling process and to synchronize the laser pulse for Ps excitation in the AEgIS experiment. In order to perform measurements of Ps excitation in Rydberg states, a new apparatus for bunching positron pulses, coming from the AEgIS positron line, was designed and built. COMSOL and SIMION softwares were used for designing a magnetic transport line and an electron optical line, which extracts positrons from the magnetic field and focus them on the nanochanneled Si sample. More, a buncher device, which spatio-temporally compresses the positron bunches, was built and a fast circuit for supplying the 25 buncher electrodes with a parabolic shaped potential was designed and tested. According to the simulations, at the target position the device will deliver positrons with an energy ranging from 6 to 9 keV, in bunches of 5 ns duration and a spot of 2.5 mm in diameter. By using this apparatus, first measurements for the optimization of Ps excitation in Rydberg states and studies on the Ps levels with and without magnetic field will be performed. At a later stage investigations of Ps spectroscopy or of Ps laser cooling with the same apparatus could be achievable for the first time

Search for geo-neutrinos and rare nuclear processes with Borexino

Borexino was designed to measure solar neutrinos in the MeV or sub-MeV energy range. The unprecedented radiopurity of the detector has allowed the detection of geo-neutrinos and the determination of competitive limits on the rate of rare or forbidden processes. In this paper, we review the basic principle of neutrinos and antineutrinos detection in Borexino and we describe the results of the geo-neutrinos measurements and their implications. Then we summarize the search for Borexino events correlated with gamma ray bursts and for axion induced signals, and the limits achieved on Pauli forbidden transitions and on the electron charge conservation

Pulsed production of antihydrogen

AbstractAntihydrogen atoms with K or sub-K temperature are a powerful tool to precisely probe the validity of fundamental physics laws and the design of highly sensitive experiments needs antihydrogen with controllable and well defined conditions. We present here experimental results on the production of antihydrogen in a pulsed mode in which the time when 90% of the atoms are produced is known with an uncertainty of ~250 ns. The pulsed source is generated by the charge-exchange reaction between Rydberg positronium atoms—produced via the injection of a pulsed positron beam into a nanochanneled Si target, and excited by laser pulses—and antiprotons, trapped, cooled and manipulated in electromagnetic traps. The pulsed production enables the control of the antihydrogen temperature, the tunability of the Rydberg states, their de-excitation by pulsed lasers and the manipulation through electric field gradients. The production of pulsed antihydrogen is a major landmark in the AE$$\bar{g}$$ ḡ IS experiment to perform direct measurements of the validity of the Weak Equivalence Principle for antimatter.</jats:p