32025587
High-precision B(E2) measurements of semi-magic 58,60,62,64Ni by Coulomb excitation
J. M. Allmond,1 B. A. Brown,2,3 A. E. Stuchbery,4 A. Galindo-Uribarri,5,6 E. Padilla-Rodal,7 D. C. Radford,5 J. C. Batchelder,8 M. E. Howard,9 J. F. Liang,5 B. Manning,9 R. L. Varner,5 and C.-H. Yu5 1JINPA, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA 2National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA 3Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, USA 4Department of Nuclear Physics, Australian National University, Canberra ACT 0200, Australia 5Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA 6Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA 7Instituto de Ciencias Nucleares, UNAM, AP 70-543, 04510 Mexico, D.F., Mexico 8UNIRIB, Oak Ridge Associated Universities, Oak Ridge, Tennessee 37831, USA 9Department of Physics and Astronomy, Rutgers University, New Brunswick, New Jersey 08903, USA (Received 13 May 2014; revised manuscript received 7 August 2014; published 15 September 2014)
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.
53131853
Testing electroweak baryogenesis with future colliders
A bstractElectroweak Baryogenesis (EWBG) is a compelling scenario for explaining the matter-antimatter asymmetry in the universe. Its connection to the electroweak phase transition makes it inherently testable. However, completely excluding this scenario can seem difficult in practice, due to the sheer number of proposed models. We investigate the possibility of postulating a “no-lose” theorem for testing EWBG in future e+e− or hadron colliders. As a first step we focus on a factorized picture of EWBG which separates the sources of a stronger phase transition from those that provide new sources of CP violation. We then construct a “nightmare scenario” that generates a strong first-order phase transition as required by EWBG, but is very difficult to test experimentally. We show that a 100 TeV hadron collider is both necessary and possibly sufficient for testing the parameter space of the nightmare scenario that is consistent with EWBG.
38643705
BEPCII Interaction Region Design and Construction Status
BEPC (Beijing Electron Positron Collider) is now upgrading to a double-ring collider which requires a new storage ring to be built in the existing tunnel. A new and compact interaction region (IR) has been designed to allow a peak luminosity of 1033cm-2s-1from an equal beam energy of 1.89 GeV, a crossing angle, 93 bunches with maximum beam current of 0.91 A . The multi-purpose superconducting magnets and conventional dual aperture quadrupoles are used as final focusing quadrupole in the interaction region. The two beams collide at the interaction point with a crossing angle of ± 11 mrad and further beams separation is enhanced with the help of a septum bending magnet which locates just beyond the superconducting magnet and acts on the outgoing beam lines only. This paper will describe the IR design and the construction status.
119013150
Looking for parity nonconservation from strong interactions beyond QCD
Quantum Chromodynamics (QCD), the gauge eld theory describing the strong interactions of colored quarks and gluons in the Standard Model 12 , has been extraordinarily successful in describing physics in both non-perturbative and perturbative regimes. Using the positivity of the Euclidean path integrand for Yang-Mills theory, Vafa and Witten proved that QCD does not spontaneously break parity or CP if = 0 3 . CP conservation in the strong interactions is necessitated by the extreme smallness of experimental upper bounds on the neutron electric dipole moment a . It has been suggested that heavy ion collisions may form metastable phases which allow for parity nonconservation 5 . An induced charge separation along the angular momentum vector of the collision would create an electric dipole moment of the hot gluon matter. There are ongoing searches by the STAR collaboration 6 at the Relativistic Heavy Ion Collider (RHIC) to establish such an eect. Also, parityviolating eects can be induced by topological solutions in QCD.