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We discuss the scientific motivation, possible experiments, and beam requirements for measurements of parity violation in photonuclear reactions at an intensity upgraded HIGS facility, HIGS2.
A γ-ray linear polarization measurement has been performed to directly determine the parities for the levels in 146Gd nucleus. High-spin states in this nucleus were populated in a reaction 115In + 34S at 140 MeV incident energy. Linearly polarized γ - rays emitted from oriented states were measured using a Compton polarimeter consisting of an array of 8 Compton-suppressed Clover detectors. Unambiguous assignments of the spin and parity have been made for most of the observed levels and changes made in the previously reported spin-parity assignments for a few levels. Shell model calculations performed with judicious truncation over the π(gdsh) valence space interpret the structure of only the low-lying levels up to Jπ = 19+ and 9-. N = 82 neutron-core breaking is found to be essential for high spin states with excitation energies Ex > 7 MeV.
Nuclei in the upper-$sd$ shell usually exhibit characteristics of spherical single particle excitations. In the recent years, employment of sophisticated techniques of gamma spectroscopy has led to observation of high spin states of several nuclei near A$\simeq$ 40. In a few of them multiparticle, multihole rotational states coexist with states of single particle nature. We have studied a few nuclei in this mass region experimentally, using various campaigns of the Indian National Gamma Array setup. We have compared and combined our empirical observations with the large-scale shell model results to interpret the structure of these nuclei. Indication of population of states of large deformation has been found in our data. This gives us an opportunity to investigate the interplay of single particle and collective degrees of freedom in this mass region.
The {\sc Majorana Demonstrator will search for the neutrinoless double-beta decay of the isotope Ge-76 with a mixed array of enriched and natural germanium detectors. The observation of this rare decay would indicate the neutrino is its own antiparticle, demonstrate that lepton number is not conserved, and provide information on the absolute mass scale of the neutrino. The {\sc Demonstrator} is being assembled at the 4850-foot level of the Sanford Underground Research Facility in Lead, South Dakota. The array will be situated in a low-background environment and surrounded by passive and active shielding. Here we describe the science goals of the {\sc Demonstrator} and the details of its design.
We performed an experimental search for the bound state singlet deuteron predicted in some microscopic calculations. The experiment consists in a high statistics measurement of gamma ray spectra after thermal neutron capture by hydrogen nuclei. The upper limit is obtained for the probability of the 3S1 - 1S0 -transition population of the deuteron singlet bound state with the bound energy in the interval 25-125 keV.
In this thesis, I show my Ph.D. work on event-by-event hydrodynamic simulations for relativistic heavy-ion collision. I show that event-by-event hydrodynamic simulations have become an indispensable tool for studying relativistic heavy-ion collisions and how it can be used to explain many phenomena. Different chapters focus on different topics; it mainly includes: Chap 2: comparison between single-shot hydrodynamics event-by-event hydrodynamic simulations. Chap 3: using the elliptic and triangular flow data measured by the ALICE collaboration at the LHC to constrain initial condition models. Chap 4: study on correlations between event-plane angles. Chap 5: how resonance decay calculation can be speed up by a factor of 10. Chap 6: study on fluctuations of event planes angle Ψn(pT) and their theoretical and experimental consequences. Chap 7: sampling particles according to the Cooper-Frye formula.
We report on two pion-photoproduction measurements in the threshold region conducted in the A2 collaboration at MAMI with the almost 4π Crystal Ball detector. The first was with a linearly polarized photon beam and unpolarized liquid-hydrogen target. The data analysis is now complete and the linearly polarized beam asymmetry along with differential cross sections provide the most stringent test to date of the predictions of Chiral Perturbation Theory and its energy region of convergence. More recently, a measurement was performed using both circularly polarized photons and a transversely polarized butanol frozen-spin target, with the goal of extracting both the target and beam-target asymmetries. From these we intend to extract πN scattering sensitive information for the first time in photo-pion reactions. This will be used to test isospin conservation and further test dynamics of chiral symmetry breaking in QCD as calculated at low energies by Chiral Perturbation Theory.
We present the predictions of a hydrodynamic model for the flow observables recently measured in the highest-multiplicity p+Pb collisions at the LHC. We focus o the ridge phenomenon, which provides an important probe of the long-range dynamics and may be used to support the collective interpretation of the p+A data.
One of the main goals of heavy-ion collision experiments is to study the structure of the QCD phase diagram. The QCD phase diagram is typically plotted as temperature ($T$) vs. baryon chemical potential ($μ_{B}$). The statistical thermal model THERMUS compared to experimental data provides chemical freeze-out parameters such as temperature, baryon chemical potential and strangeness saturation factor ($γ_{s}$). However, the values of these parameters depend on models and their underlying assumptions, such as the nature of the ensemble used, particle ratios vs. particle yields, and the treatment of feed-down contributions to particle yields. In these proceedings, we report on a systematic study of chemical freeze-out parameters using THERMUS, as a function of collision centrality and collision energies ($\sqrt{s_{NN}} =7.7-200$ GeV). These studies are performed with the string melting version of A Multi-Phase Transport (AMPT) model. A comparison is presented of freeze-out parameters between grand-canonical vs. strangeness canonical ensembles, particle yields vs. ratios, with and without feed-down contributions to the particle yields. The main aim is to evaluate the sensitivity of the thermal model fits to various model assumptions. This is an important study for understanding corresponding experimental results from the beam energy scan program at RHIC.
We present an overview of the status of the studies related to the phase diagram of strong interactions through high-energy nuclear collisions. We discuss both the theoretical and experimental status of establishing the various QCD phase structures in the phase diagram, such as, quark-gluon phase, quark-hadron crossover, crossover temperature, phase boundary and critical point.
To improve the effective interactions in the pf shell, it is important to measure the single particle- and hole- states near the N=28 shell gap. In this paper, the neutron spectroscopic factors of hole-states from the unstable neutron-rich 45Ar (Z=18, N=27) nucleus have been studied using 1H(46Ar, 2H)45Ar transfer reaction in inverse kinematics. Comparison of our results with the particle-states of 45Ar produced in 2H(44Ar, H)45Ar reaction shows that the two reactions populate states with different angular momentum. Using the angular distributions, we are able to confirm the spin assignments of four low-lying states of 45Ar. These are the ground state (f7/2), the first-excited (p3/2), the s1/2 and the d3/2 states. While large basis shell model predictions describe spectroscopic properties of the ground and p3/2 states very well, they fail to describe the s1/2 and d3/2 hole-states.
This report is presented the level densities and gamma strength function which is extracted from primary gamma transitions of (n,2g) measurement on the Dalat Nuclear Research Reactor (DNRR). The comparisons with others results and model calculations, there are outside the scope of uncertainty. These research results are showed that having of complement research for deformed nucleus in order to evaluate nuclear structure models.
In the Standard Model, lepton universality refers to the identical electroweak gauge interactions among charged leptons. The measurement of the branching ratio $R_{e / μ} = \frac{Γ(π\rightarrow\ e ν)}{Γ(π\rightarrowμν)}$ is one of the most stringent tests of lepton universality between the first two generations. The TRIUMF PIENU experiment aims at the most precise test of universality measuring $R_{e / μ}$ with 0.1% precision. The measurement will provide improved constraints to physics beyond the Standard Model or uncover new scenarios if a disagreement is found.
We discuss unitarity tests of the neutrino mixing (PMNS) matrix. We show that the combination of solar neutrino experiments, medium-baseline and short-baseline reactor antineutrino experiments make it possible to perform the first direct unitarity test of the PMNS matrix. In particular, the measurements of Daya Bay and JUNO (a next generation medium-baseline reactor experiment) will lay the foundation of a precise unitarity test of $|U_{e1}|^2 + |U_{e2}|^2 + |U_{e3}|^2 = 1 $. Furthermore, the precision measurement of $\sin^22θ_{13}$ in both the $\barν_e$ disappearance and the $ν_e$ appearance (from a $ν_μ$ beam) channels will provide an indirect unitarity test of the PMNS matrix. Together with the search for appearance/disappearance at very short distances, these tests could provide important information about the possible new physics beyond the three-neutrino model.
The detection efficiency of phoswich detector starts to decrease when Compton scattering becomes significant. Events with energy deposit in both scintillators, if not rejected, are not useful for spectral analysis as the full energy of the incident photon cannot be reconstructed with conventional readout. We show that once the system response is carefully calibrated, the full energy of those double deposit events can be reconstructed using a waveform digitizer as the readout. Our experiment suggests that the efficiency of photopeak at 662 keV can be increased by a factor of 2 given our LaBr$_3$/NaI phoswich detector.
In November 2010, the azimuthally symmetric WASA detector and the polarized proton beam of COSY, have been used to collect a high statistics sample of $\vec{p}p \rightarrow ppη$ reactions in order to determine the analyzing power as a function of the invariant mass spectra of the two particle subsystems. Here, we show studies of the influence of the beam and target characteristics such as location and direction on the determination of the polarization.
The last decade has been the decade of nanotechnology, a length scale which is of particular interest since it is here that we see the transition from the classical to the quantum world. In this transition to the quantum regime new phenomena appear that have proven valuable in a wide range of applications. This whitepaper focusses on the simplest nanotechnology, the spherical nanoparticles and their possible application to particle physics.
The similarity renormalization group is used to transform a general Dirac Hamiltonian into diagonal form. The diagonal Dirac operator consists of the nonrelativistic term, the spin-orbit term, the dynamical term, and the relativistic modification of kinetic energy, which are very useful to explore the symmetries hidden in the Dirac Hamiltonian for any deformed system. As an example, the relativistic symmetries in an axially deformed nucleus are investigated by comparing the contributions of every term to the single particle energies and their correlations with the deformation. The result shows that the deformation considerably influences the spin-orbit interaction and dynamical effect, which play a critical role in the relativistic symmetries and its breaking.