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The Ce+BAF project at the Thomas Jefferson National Accelerator Facility intends to develop over the coming years a high-duty cycle, high intensity, and high polarization positron beam to serve a unique Nuclear Physics experimental program. It generically comprises the study of the effects of the two- and multi-photon exchange mechanisms, the investigation of the nuclear structure at the nucleonic and partonic scales, and tests of the standard model of particle physics and interactions. This proceedings illustrates this physics program through specific examples and presents the Ce+BAF positron injector concept. [ABSTRACT FROM AUTHOR]

EGS5 is a code system for photons, electrons, and positrons transport simulations. One of the main purposes of the EGS5 is for medical physics Monte Carlo simulations, due its highly accurate modelling physics for radiation. The EGS5 system is written in FORTRAN, and for running a simulation the user must prepare a FORTRAN user-code file, and two other input files, one for materials and the second for geometry. The EGS-SMS code was developed to simplify the users' preparations and running EGS5 simulations. The EGS-SMS code is a shell developed using PYTHON that implements plain text format command lines into the EGS5 code system to run the user's simulations. [ABSTRACT FROM AUTHOR]

Abstract. In electron-positron annihilation, the process of e+e−→ χc1 can occur via the production of two virtual photons or through neutral current, therefore being suppressed with respect to the normal annihilation process via one virtual photon. Using a dedicated scan sample around the χc1 mass, the direct production of χc1 has been established for the first time in experiments. This provides a new approach for the study of the internal nature of hadrons. [ABSTRACT FROM AUTHOR]

Despite mesons being one of the longest known type of particles, there are still many open questions. Besides well understood states that can be clearly attributed to meson nonets, there are many candidates which could have an exotic nature instead. Such exotic particles e.g. glueballs, hybrids and tetraquarks can be favorably studied in clean, gluon rich environments. The BE-SIII experiment, which is in operation at the BEPCII electron-positron collider in Beijing since 2009, has collected world leading high statistic data samples in the charmonium region. This allows to study rare reactions that are considered to be suppressed. This offers unique possibilities to study exotic QCD states in the charmonium sector, but also the light meson spectrum which can be ac cessed via charmonium decays. Especially radiative J/ψ decays offer a gluon rich environment in which glueballs and hybrid states can be expected. Since these states are often hard to identify and disentangle, partial wave analysis are needed to determine the different contributions. [ABSTRACT FROM AUTHOR]

The study of neutrinoless double beta decay (DBD) has attracted much attention because it can provide valuable information about the mass and the nature of the neutrino. DBD itself is also of interest in nuclear physics. While DBD has been observed in about a dozen nuclei, the positron DBD (β+β+/EC-β +) continues to be elusive. An important signature for β +β + decay is the simultaneous emission of four 511 keV gamma rays, and the coincident detection of these gamma rays can improve the measurement sensitivity. This paper presents an estimation of sensitivity for EC-β+and β +β+, employing coincidence measurement with two high-purity Ge (HPGe) detectors. Simulations for coincident detection efficiency (εc) of 511 keV gamma rays with two HPGe detectors were carried out using GEANT4 for different source geometries to optimize the mass efficiency product (Mεc). A source of size 55 mm × 55 mm × 5 mm (thickness) sandwiched between the front faces of the detectors was found to be optimal for two pairs of 511 keV gamma rays in the present detector setup. The coincident background was estimated at sea level with moderate lead shielding. With this setup, the sensitivity for T1/2 measurement of EC-β+in 112Sn and β +β+ in 106Cd was estimated to be ∼1019–1020 years for one year of measurement time. [ABSTRACT FROM AUTHOR]

The propagation of nonlinear dust ion acoustic (DIA) solitary wave (SW) in dusty plasma consisting of positive and negative ions, nonthermally distributed electrons and positrons is studied in presence of magnetic field effect. The three-dimensional Zakarov-Kuznetsov (Z-K) equation is derived, using reductive perturbation technique and the solution is obtained using tan-hyperbolic method. It is observed that the bifurcation point (the point where two streams of nonlinear waves split) for compressive and rarefactive solitary waves are found to be on opposite sides of each other. Also, it is seen that at a certain value of nonthermal electrons in plasma, the transition from compressive to rarefactive solitary wave is observed. [ABSTRACT FROM AUTHOR]

The propagation of small amplitude dust ion acoustic (DIA) solitary waves (SW) in four component relativistic plasma with nonthermal electrons, mobile positively charged ions and positrons, and negatively charged massive dust particles is discussed in this paper. The Korteweg-de-Vries (K-dV) nonlinear wave equation is numerically derived using the reductive perturbation approach. The role of streaming positron beam on the characteristic features of solitary waves are observed and the possible region of the formation of ion acoustic (IA) SW is analysed. The findings of this work will help in the understanding of the Earth's upper atmosphere (Ionosphere's Aurora region) as well as the space plasmas. [ABSTRACT FROM AUTHOR]

A triple coincidence digital positron lifetime setup (PALS) was combined with a coincidence Doppler broadening system (CDBS) in our laboratory to handle both measurements at the same time with the same positron source. Similar commonly used setup AMOC - Age-Momentum Correlation needs time correlation between positron lifetime and positron momentum. The exact correlation from the same positron annihilation event is not possible with this setup. Two photons from positron annihilations and 1274keV photons are used in triple coincidence PALS, and another annihilation photons spread in a line perpendicular to this plane are used for CDBS. In the CDBS part, 1274keV photons are used for steady energy calibration of the spectra. Therefore, photons detected in CDBS and PALS parts are not from the same annihilation event. From a long-term stability view, the temperature, the positron source activity and the stability of the power source are correlated and can be used to determine their impact on both measurements. [ABSTRACT FROM AUTHOR]

Due to the great effect of defects on the properties of materials including strength, ductility, resistivity and opacity, many techniques are used in defect detecting. In this work, positron annihilation lifetime technique (PALT), positron annihilation doppler Broadening technique (PADBT), and Vickers hardness (HV) were used to study the influence of plastic deformation on the properties of 3004 Al-alloy. The mean crystallite size measured by Positron annihilation lifetime technique, doppler Broadening technique and Vickers hardness test (HV) decrease as thickness reduction increases. A good correlation between the three techniques (PALT, PADBT and HV) for mean crystallite size was found. The dislocation density values at different degrees of deformation by VHT are larger compared to DBT and PALT. [ABSTRACT FROM AUTHOR]

Gamma rays from nuclear processes such as radioactive decay and de-excitations are among the most-direct tools to witness the production and existence of specific nuclei and isotopes in and near cosmic nucleosynthesis sites. With space-borne instrumentation such as NuSTAR and SPI/INTEGRAL, and experimental techniques to handle a substantial instrumental background from cosmic-ray activations of the spacecraft and instrument, unique results have been obtained, from diffuse emissions of nuclei and positrons in interstellar surroundings of sources, as well as from observations of cosmic explosions and their radioactive afterglows. These witness non-sphericity in supernova explosions and a flow of nucleosynthesis ejecta through superbubbles as common source environments. Next-generation experiments that are awaiting space missions promise a next level of observational nuclear astrophysics. [ABSTRACT FROM AUTHOR]

A triple coincidence digital positron lifetime setup is commonly used in the laboratory of the positron annihilation spectroscopy at the Slovak Technical University for more than ten years. During its operation, several changes and upgrades were accomplished. With the process being carried out, enhancement of the timing resolution and reduction of the setup complexity were achieved. Requirements of other laboratories, like automatic time measurement, were included in the QtPALS software developed at the institute of nuclear and physical engineering in Bratislava. Benefits of triple coincidence, commonly used in positron annihilation spectra background suppression in samples containing 60Co, are also in better time resolution, which outbalanced increasing of the measurement time. Used custom FPGA firmware in DRS4 evaluation board from Paul Scherrer Institute allows use of the digital positron lifetime setup without external coincidence trigger chain. [ABSTRACT FROM AUTHOR]

We report the status of the CMS full simulation for Run 3. During the long shutdown of the LHC a significant update has been introduced to the CMS code for simulation. The CMS geometry description is reviewed. Several important modifications were needed. CMS detector description software is migrated to the DD4Hep community developed tool. We will report on our experience obtained during the process of this migration. Geant4 10.7 is the CMS choice for Run 3 simulation productions. We will discuss arguments for this choice, the strategy of adaptation of a new Geant4 version, and will report on the physics performance of the CMS simulation. A special Geant4 Physics List configuration FTFP_BERT_EMM will be described, which provides a compromise between simulation accuracy and CPU performance. A significant fraction of time for simulation of CMS events is spent on tracking of charged particles in a magnetic field. In the CMS simulation a dynamic choice of Geant4 parameters for tracking in field is implemented. A new method is introduced into simulation of electromagnetic components of hadronic showers in the electromagnetic calorimeter of CMS. For low-energy electrons and positrons a parametrization of GFlash type is applied. Results of tests of this method will be discussed. In summary, we expect about 25% speedup of the CMS simulation production for Run 3 compared to the Run 2 simulations. [ABSTRACT FROM AUTHOR]

High intensity lasers (>1019 W/cm2) produce relativistic electrons when they interact with matter. The high energy electrons upon incidence on a solid target produce secondary emissions like protons, neutrons, positrons, x-ray emission and γ-rays1. Gamma rays produce from this interaction can be used to induce photoneutron reaction in a material, thereby producing short-lived isotopes or isomers2. The isotopes or isomers produced can be used for diagnosing the radiation flux and directionality3. Materials with short half-lives (in μs to ms time scale) are of interest as a diagnostic for shot to shot measurement of parameters in high repetition lasers (10 Hz), since they decay well before the incidence of the subsequent pulse on the material. For understanding the working of this diagnostic, systematic studies of decay of the isotopes/isomers produced and the attenuation of γ-rays in the material are necessary. The design and efficiency of a diagnostic for characterizing γ-rays using the method of nuclear activation for 10 Hz high repetition laser is presented. [ABSTRACT FROM AUTHOR]