119191703
Low background signal readout electronics for the Majorana Demonstrator
The Majorana Demonstrator is a planned 40 kg array of Germanium detectors intended to demonstrate the feasibility of constructing a tonne-scale experiment that will seek neutrinoless double beta decay (0νββ) in 76Ge. Such an experiment would require backgrounds of less than 1 count/tonne-year in the 4 keV region of interest around the 2039 keV Q-value of the ββ decay. Designing low-noise electronics, which must be placed in close proximity to the detectors, presents a challenge to reaching this background target. This paper will discuss the Majorana collaboration's solutions to some of these challenges.
119248652
MAJORANA Collaboration's Experience with Germanium Detectors
The goal of the \textsc{Majorana} \textsc{Demonstrator} project is to search for 0$\nu\beta\beta$ decay in $^{76}\mathrm{Ge}$. Of all candidate isotopes for 0$\nu\beta\beta$, $^{76}\mathrm{Ge}$ has some of the most favorable characteristics. Germanium detectors are a well established technology, and in searches for 0$\nu\beta\beta$, the high purity germanium crystal acts simultaneously as source and detector. Furthermore, p-type germanium detectors provide excellent energy resolution and a specially designed point contact geometry allows for sensitive pulse shape discrimination. This paper will summarize the experiences the \textsc{Majorana} collaboration made with enriched germanium detectors manufactured by ORTEC$^{\circledR}$. The process from production, to characterization and integration in \textsc{Majorana} mounting structure will be described. A summary of the performance of all enriched germanium detectors will be given.
118542562
Status of the MAJORANA DEMONSTRATOR
The MAJORANA Collaboration is constructing the MAJORANA DEMONSTRATOR, an ultra-low background, modular, HPGe detector array with a mass of 44-kg (29 kg 76Ge and 15 kg natGe) to search for neutrinoless double beta decay in Ge-76. The next generation of tonne-scale Ge-based neutrinoless double beta decay searches will probe the neutrino mass scale in the inverted-hierarchy region. The MAJORANA DEMONSTRATOR is envisioned to demonstrate a path forward to achieve a background rate at or below 1 count/tonne/year in the 4 keV region of interest around the Q-value of 2039 keV. The MAJORANA DEMONSTRATOR follows a modular implementation to be easily scalable to the next generation experiment. First, the prototype module was assembled; it has been continuously taking data from July 2014 to June 2015. Second, Module 1 with more than half of the total enriched detectors and some natural detectors has been assembled and it is being commissioned. Finally, the assembly of Module 2, which will complete MAJORANA DEMONSTRATOR, is already in progress.
123625266
Interaction region design and realization for the Beijing Electron Positron Collider
The Beijing Electron Positron Collider (BEPC) has been upgraded as a double-ring factory-like collider (BEPCII). A compact interaction region (IR), which is the most complicated region in the BEPCII, has been designed to afford a peak luminosity of 1 x 10(33) cm(-2) s(-1) with an equal beam energy of 1.89 GeV, a cross angle of +/-11 mrad, 93 bunches and maximum beam current of 0.91 A. All the components of the IR have been fabricated successfully. The design and realization of the interaction region for the BEPCII will be introduced in detail. (C) 2009 Elsevier B.V. All rights reserved.
119291201
Asymmetric left-right model and the top pair forward-backward asymmetry
The forward-backward asymmetry measurement in top-pair production at the Tevatron is about $2\ensuremath{\sigma}$ from the standard model prediction. We propose an asymmetric left-right model, which includes a ${W}^{\ensuremath{'}}$ boson with a right-handed coupling of down to top quark, and a ${Z}^{\ensuremath{'}}$ boson with diagonal couplings to the up, top, and down quarks with ${M}_{{W}^{\ensuremath{'}}}\ensuremath{\approx}175\text{ }\text{ }\mathrm{GeV}$ and ${M}_{{Z}^{\ensuremath{'}}}\ensuremath{\approx}900\text{ }\text{ }\mathrm{GeV}$. The model accounts for the asymmetry while remaining consistent with the top-pair total cross section and invariant mass distribution.
118567857
PROPOSAL OF AN INVERSE LOGARITHM SCALING LAW FOR THE LUMINOSITY EVOLUTION
A scaling law for the time-dependence of the dynamic aperture, i.e., the region of phase space where stable motion occurs, was proposed in previous papers, about ten years ago. It was showed that dynamic aperture has a logarithmic dependence on time, which would be suggested by some fundamental theorems of the theory of dynamical systems. Such a scaling law was recently extended also to the intensity evolution in a storage ring. In this paper, inspired by these results, and inverse logarithm scaling law for the luminosity in a circular collider is proposed. Such a time-dependence is then tested against the data from the LHC physics runs and also with some examples from other machines. The results are presented and discussed in detail.
121335136
Design and field measurement of the BEPC-II interaction region dual-aperture quadrupoles
With the Beijing Electron Positron Collider upgrade project (BEPC-II), two dual-aperture septum-style quadrupole magnets are used in the interaction region for the final focusing of the electron and positron beams. The BEPC-II lattice design calls for the same high quality integral quadrupole field and large good field region in both apertures for each magnet. Two-dimensional contour optimization and pole-end chamfer iteration are used to minimize the systematic harmonic errors. Unexpected non-systematic errors induced by the unsymmetrical structure and the manufacturing errors are compensated with the pole-end shimming. Magnet measurements with rotating coils are performed to guide and confirm the magnet design. This paper discusses the design consideration, optimizing procedure and measurement results of these dual-aperture magnets.