117722455
Neutron-induced 235 U fission spectrum measurements using liquid organic scintillation detectors
Measurements have been performed at Los Alamos Neutron Science Center to acquire neutron fission spectra of ${}^{235}$U in the energy range between 0.5 and 10 MeV. These new data complement the currently available experimental data, which are not well known in the energy range below 1 and above 5 MeV. Organic liquid scintillation detectors (EJ-309s) were used together with a digital data-acquisition system. The EJ-309 detectors show excellent pulse shape discrimination capabilities and this is vital for identifying only neutron pulses and rejecting $\ensuremath{\gamma}$-ray pulses. The measurement data show the dependence of average fission neutron energy as a function of the inducing neutron energy. The data agree well with previously published measurements and Watt spectra fits for energies up to tens of MeV. At high fission-inducing neutron energies the spectrum deviates from Watt-spectra fits. The increased energy deposited in higher energy neutron-induced fissions does not significantly increase emitted fission neutron energies for up to 10 MeV. A significant decrease in neutron energy around second-chance fission cannot be observed beyond the current measurement uncertainties.
119859464
A novel method for direct investigation of dark matter
The Materia OSCura A Bolle (MOSCAB) experiment uses a new technique for Dark Matter search. The Geyser technique is applied to the construction of a prototype detector with a mass of 0.5 kg and the encouraging results are reported here; an accent is placed on a big detector of 40 kg in construction at the Milano Bicocca University and INFN.
122721397
Analysis of Neutron and Photon Detection Position for the Calibration of Plastic (BC-420) and Liquid (BC-501) Scintillators
This report presents the results of the neutron and photon calibration of a Bicron BC-420 plastic scintillator and a BC-501 liquid scintillator using a set of reference gamma sources and a Cf-252 source. The position of neutron and photon detection inside the scintillators as a function of energy is investigated by Monte Carlo simulation.
21278706
Submillimeter-resolution radiography of shielded structures with laser-accelerated electron beams
We investigate the use of energetic electron beams for high-resolution radiography of flaws embedded in thick solid objects. A bright, monoenergetic electron beam (with energy >100 MeV) was generated by the process of laser-wakefield acceleration through the interaction of 50-TW, 30-fs laser pulses with a supersonic helium jet. The high energy, low divergence, and small source size of these beams make them ideal for high-resolution radiographic studies of cracks or voids embedded in dense materials that are placed at a large distance from the source. We report radiographic imaging of steel with submillimeter resolution.
10071539
MeV-energy x rays from inverse compton scattering with laser-wakefield accelerated electrons.
We report the generation of MeV x rays using an undulator and accelerator that are both driven by the same 100-terawatt laser system. The laser pulse driving the accelerator and the scattering laser pulse are independently optimized to generate a high energy electron beam (>200  MeV) and maximize the output x-ray brightness. The total x-ray photon number was measured to be ∼1×10(7), the source size was 5  μm, and the beam divergence angle was ∼10  mrad. The x-ray photon energy, peaked at 1 MeV (reaching up to 4 MeV), exceeds the thresholds of fundamental nuclear processes (e.g., pair production and photodisintegration).
121954370
Plutonium metal vs. oxide determination with the pulse-shape-discrimination-capable plastic scintillator EJ-299-33
Abstract Neutron measurements can be used to distinguish plutonium in metal or oxide form, a capability that is of great interest in nuclear nonproliferation, treaty verification, and other applications. This paper describes measurements performed on well-characterized samples of plutonium oxide and plutonium metal using the pulse-shape-discrimination-capable plastic scintillator EJ-299-33. Results are compared to those obtained with a same-sized detector cell using the liquid scintillator EJ-309. The same optimized, digital pulse shape discrimination technique is applied to both detectors and the neutron pulse height distributions are compared. Results show that the EJ-299-33 plastics can be successfully used for plutonium measurements, where the gamma ray to neutron detection ratio is much higher than for typical radioactive sources. Results also show that EJ-299-33 detectors can be used to characterize plutonium samples, specifically to discriminate between plutonium metal and oxide.
118429407
The spatial alignment of theMuon Detector for the LHCbexperiment.
The phenomenology of particle physics is well described by the Standard 
Model. However, some of the parameters of the model are not 
predicted and have to be experimentally determined, as for instance, the 
four parameters of the quark mixing matrix, the Cabibbo-Kobayashi- 
Maskawa (CKM) matrix. One of these parameters, the phase of the 
CKM matrix, is responsible of the violation of the CP symmetry that 
was identied as one of the causes for the asymmetry between matter 
and anti-matter in the Universe [1]. 
LHCb is one of the four experiments of particle physics at the Large 
Hadron Collider accelerator built at CERN. 
The LHCb experiment is dedicated to high precision measurement of 
CP violating parameters in the system of B mesons. The large samples 
of B − B pairs that will be produced allow to measure very rare B 
decays like Bs → +−. The branching ratio predicted by the Standard 
Model for this decay is of the order of O(10−9), but it can receive large 
contributions by virtual processes involving new particles. 
The challenge of the LHCb experiment is to efficiently discriminate 
the events of interest from the background produced by the p − p collisions. For this reason the experiment is equipped not only with specific 
detectors, but also with an efficient trigger system, in which the Muon 
Detector plays an important role. The Muon Detector task, in the first 
stage of the trigger system, is the detection of muons with high transverse 
momentum1. Moreover, in the high level trigger and in the off-line 
reconstruction the Muon Detector provides the muon identication. The 
information on muons in the nal states of B meson decays are used 
by the tagging algorithms for the determination of the b avour of the 
decaying B mesons. This procedure is of great relevance in CP violation 
measurements. 
Because of the role it plays in the experiment, it is crucial to know 
the actual position of the Muon Detector, and to monitor it during the 
time. This is the aim of the software alignment of the detector and the 
subject of this thesis. 
The software procedure to align the Muon Detector, locally and globally, 
has been carried out developing specic algorithms for the track nding 
and reconstruction. The reconstructed tracks have been expressed in 
the standard LHCb track format and tted with the default LHCb track 
t method. The Muon Detector software alignment procedure has been 
tested with three kinds of data: Monte Carlo muons coming from the 
interaction point, real cosmic rays and Monte Carlo cosmic data. The 
real cosmic rays, analysed in this work, have been the rst experimental 
data ever acquired by LHCb. 
This thesis is divided in the following chapters: 
Chapter 1 describes the CP violation in the Standard Model of particles 
with the phenomenology of interest in the LHCb experiment. 
Chapter 2 briefly escribes LHC and then discusses all the detectors 
that constitute the LHCb experiment. 
Chapter 3 is entirely dedicated to the Muon Detector for its relevance 
to this thesis. 
In Chapter 4 the alignment methods used are described. 
Chapter 5, after a brief description of the LHCb software organisation, 
discusses the first test of the global alignment procedure applied to the 
Muon Detector, and performed with Monte Carlo data of single muons 
coming from the interaction point. 
With real cosmic rays a local alignment of the Muon Detector was 
performed. In addition a preliminary study for a relative alignment of 
the detector with respect to the Outer Tracker was also carried on. This 
is the subject of Chapter 6. 
In Chapter 7 a Monte Carlo cosmic data sample has been produced 
for testing the local alignment performed with real cosmic rays and for 
studying local systematics arising from the acceptance of the Muon Detector 
unsuited for the cosmic ray geometry.
34636075
The LHCb Muon detector alignment
The Muon detector of the LHCb experiment is used in both trigger steps (Level-0 and High Level Trigger) and provides also the off-line Muon Identification. Therefore the proper alignment of the detector is needed and it should be monitored during the data taking. In this document the methods used for the alignment of the Muon detector and the results obtained are presented. Two sets of data have been analyzed: a sample of Monte Carlo tracks simulated from the interaction point, and, for a first check with real data on the survey measurements, the cosmic rays acquired during the commissioning in September and October 2008.