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Study of b-quark production asymmetry with quantum machine learning techniques at the LHCb experiment
Get PDFThe precise determination of the b-quark pair-production asymmetry is important not only as a test of the Standard
Model of Particle Physics but also to investigate possible sources of New Physics. At the LHCb experiment, that takes
data at the LHC proton-proton collider at CERN, where b-quarks are copiously produced, the Forward-Central asymmetry
in the b-quark pair-production has been measured at the center of mass energy of 7 TeV. The result is consistent with
the Standard Model expectation within the experimental error. However, additional measurements of such an observable
need to be performed at higher energies and with an increased number of events, in order to reduce the uncertainties
and to put constraints on New Physics models. The final uncertainty on asymmetry is strongly related to the ability of
identifying the flavor (u,d,s vs c vs b) and the charge (b vs anti-b) of the quark producing the jet in the detector
(jet tagging). At the LHCb experiment, jet tagging exploits the excellent capability of the detector to precise reconstruct
vertices displaced with respect to the interaction point, which allow to distinguish the long-lived heavy quarks from
light quarks jets. A standard technique, called Muon Tagging, performs charge tagging by exploiting the charge correlation
between the b-quark and the muon produced in the semi-leptonic decay. However, the small branching ratio of this decay
strongly limits the efficiency of the algorithm. For this reason other inclusive algorithms, based on Machine Learning
techniques, are being developed, which aim to exploit the full jet particles substructure. In this thesis, I present new
approaches to the charge tagging of b-jets, based on Quantum Machine Learning techniques: as a general paradigm, data
are embedded in a quantum circuit through a quantum feature map; then the initial state gets processed by a variational
quantum circuit with trainable parametrized gates; finally, measurements of observables on the final state are mapped to
a binary classification label (b-jet or anti-b-jet). The models are trained on official LHCb simulated data at the center
of mass energy of 13 TeV and the tagging performance is compared with the Muon Tagging algorithm and a classical Deep
Neural Network model. Finally, the precision on the Forward-Central asymmetry is evaluated applying the different tagging
algorithms on a sample of simulated data corresponding to the integrated luminosity of the Run2
Monte Carlo based dosimetry using PET/CT and SPECT/CT imaging in radiopharmaceutical therapy in the context of the ISOLPHARM project
Get PDFThe ISOLPHARM project has the aim of producing a set of innovative, high specific activity, carrier-free radioisotopes for target radionuclide therapy exploiting the ISOL technique at the SPES facility of INFN-LNL. The success of a particular radiopharmaceutical cancer treatment relies on an accurate assessment of the tissue response and toxicity. Since biological effects are mediated by the absorbed dose, which is defined as the energy absorbed per unit mass of tissue, internal dosimetry is of funda- mental importance because it allows for the maximization of the therapeutic effect while
minimizing the radiation burden to other organs. This thesis work
consists in the calculation of internal absorbed dose, following
radiopharmaceutical treatments — e.g. with 18 F, 111 In or 111 Ag — by means of different Monte Carlo based approaches (using the Geant4 software) coupled with PET/CT and SPECT/CT images of mice acquired by the ISOLPHARM group.
Il progetto ISOLPHARM nasce con lo scopo di produrre una serie di
radioisotopi innovativi per l’utilizzo in terapia radiofarmaceutica
sfruttando la tecnica ISOL nella facility SPES di INFN-LNL. Il
successo di un trattamento radiofarmaceutico su un tumore dipende da
un’accurata valutazione della risposta del tessuto e della tossicità.
Poiché gli effetti biologici sono mediati dalla dose assorbita,
definita come energia assorbita per unità di massa del tessuto, la
dosimetria interna è d’importanza fondamentale per permettere la
massimizzazione dell’effetto terapeutico minimizzando l’irraggiamento degli altri organi. Il lavoro di tesi consiste nel calcolo della dose assorbita internamente a seguito di trattamenti radiofarmaceutici —
per esempio con 18 F, 111 In o 111 Ag — avvalendosi di diversi
approcci basati sul metodo Monte Carlo (utilizzando il software
Geant4) abbinato a immagini PET/CT o SPECT/CT murine acquisite dal gruppo ISOLPHARM
On Non-Linear Wave-Plasma Interaction in the NORTH Tokamak Keywords: Plasma, Tokamak, Parametric Decay
Get PDFMany are the challenges that need to be addressed on the path to
commercial nuclear fusion.
A thorough understanding of the heating process is required to model correctly the behaviour of the plasma in magnetic confinement fusion and by testing the models at different sizes, the results can be scaled to reactor size devices. A common method to heat the plasma consists in injecting
high-power microwaves at the electron cyclotron frequency (ECRH). Parametric decay instabilities (PDI) can convert part of the heating power into high-power waves at frequencies different from the desired ECRH one. This can introduce losses in the heating system, affect the behaviour of the
plasma and damage diagnostic equipment not shielded appropriately. In this work, the parametric
decay of the ECRH microwaves at the upper hybrid layer in the NORTH tokamak has been studied.
By testing this effect, previously measured on the ASDEX-U tokamak, on NORTH, a much smaller device, it is possible to validate the model on a very different scale. In the first part of the work, predictions on the threshold of the effect and the frequencies of the additional waves generated by
the decay are studied using a previously developed analytical model and validated using particle in cell simulations. In the second part of the work, the decay has been experimentally studied on the NORTH tokamak by first developing a radiometer for this purpose and then performing a series of
experiments using both the radiometer and a high-frequency Langmuir probe. A threshold ranging from a few 10’s to a few 100’s of Watts and a low-frequency daughter in the range of 10-30 MHz has been predicted on NORTH, depending on experimental conditions, and the presence of the decay has
been validated in the simulations. No clear evidence of the highfrequency daughter could be found measuring either the electromagnetic waves coming out of the plasma
with a radiometer or the floating potential fluctuations using a high-frequency Langmuir probe due to the many sources of background in the system. Evidence for the low-frequency daughter has instead been found using the probe and
the signal frequency appears to change with the heating power, the pressure and the magnetic field as would be expected
Sviluppo sostenibile e decrescita felice: due facce della stessa medaglia?
No full textL'elaborato si propone inizialmente di comprendere i problemi ed i limiti delle teorie neoclassiche. Partendo da una critica sul PIL, si arrivano a esaminare due teorie economiche: sviluppo sostenibile e decrescita felice. Con il supporto di una dimostrazione analitica sulla composizione della domanda aggregata per i sostenitori della decrescita, si cerca di delineare i punti di contatto tra le due teorie