20143159
Measurements of ultracold-neutron lifetimes in solid deuterium.
We present the first measurements of the survival time of ultracold neutrons (UCNs) in solid deuterium (SD2). This critical parameter provides a fundamental limitation to the effectiveness of superthermal UCN sources that utilize solid ortho-deuterium as the source material. These measurements are performed utilizing a SD2 source coupled to a spallation source of neutrons, providing a demonstration of UCN production in this geometry and permitting systematic studies of the influence of thermal up-scatter and contamination with para-deuterium on the UCN survival time.
27442116
Cold neutron energy dependent production of ultracold neutrons in solid deuterium.
A measurement of the production of ultracold neutrons from velocity-selected cold neutrons on gaseous and solid deuterium targets is reported. The expected energy dependence for two-particle collisions with well defined neutron and Maxwell-Boltzmann distributed molecular velocities is found for the gas target. The solid target data agree in shape with the phonon density-of-states curve and provide strong evidence for the phonon model including multiphonon excitations.
119507247
Storage of Ultracold Neutrons in the Magneto-Gravitational Trap of the UCN Experiment
The UCN experiment is designed to measure the lifetime n of the free neutron by trapping ultracold neutrons (UCN) in a magneto-gravitational trap. An asymmetric bowl-shaped NdFeB magnet Halbach array confines low-field-seeking UCN within the apparatus, and a set of electromagnetic coils in a toroidal geometry provides a background holding field to eliminate depolarization-induced UCN loss caused by magnetic field nodes. We present a measurement of the storage time store of the trap by storing UCN for various times and counting the survivors. The data are consistent with a single exponential decay, and we find store = 860 19 s, within 1 of current global averages for n. The storage time with the holding field deactivated is found to be store = 470 160 s; this decreased storage time is due to the loss of UCN, which undergo Majorana spin flips while being stored. We discuss plans to increase the statistical sensitivity of the measurement and investigate potential systematic effects.
5816062
Temperature-dependent neutron scattering cross-sections for polyethylene
Abstract This note presents neutron scattering cross-sections for polyethylene at 296, 77 and 4 K derived from a new scattering kernel for neutron scattering off of hydrogen in polyethylene. The kernel was developed in ENDF-6 format as a set of S ( α , β ) tables using the LEAPR module of the NJOY94 code package. The polyethylene density of states (from 0 to sub eV) adopted to derive the new kernel is presented. We compare our calculated room temperature total scattering cross-sections and double differential cross-sections at 232 meV at various angles with the available experimental data (at room temperature), and then extrapolate the calculations to lower temperatures (77 and 4 K). The new temperature-dependent scattering kernel gives a good quantitative fit to the available room temperature data and has a temperature dependence that is qualitatively consistent with thermodynamics.
118837551
New experimental limit on the electric dipole moment of the electron in a paramagnetic insulator
We report results of an experimental search for the intrinsic Electric Dipole Moment (EDM) of the electron using a solid-state technique. The experiment employs a paramagnetic, insulating gadolinium gallium garnet (GGG) that has a large magnetic response at low temperatures. The presence of the eEDM would lead to a small but non-zero magnetization as the GGG sample is subject to a strong electric field. We search for the resulting Stark-induced magnetization with a sensitive magnetometer. Recent progress on the suppression of several sources of background allows the experiment to run free of spurious signals at the level of the statistical uncertainties. We report our first limit on the eEDM of ( 5.57 ± 7.98 ± 0.12)×10 25 e·cm with 5 days of data averaging. The search for the electric dipole moment (EDM) of elementary particles is motivated to test the discrete symmetries assumed in the Standard Model (SM) of particle physics. An account of the different transformation properties of the EDM (a polar vector) and the spin (a pseudo-vector), the fundamental physical laws governing particles must violate both time-reversal (T) and parity-inversion (P) symmetries for a fermion to acquire an EDM [1]. While the phenomena of P violation is firmly established in numerous experiments, T violation has only been observed directly in the neutral kaon system [2], with more searches in the B system underway [3]. Measurements of EDMs of elementary particles use different experimental techniques, often on low energy systems at Q ≃ 0, to probe the physics of T violation (with no flavor-changing) at energy scales higher than tens of TeV, and could provide information complementary to that from high-energy collider experiments on the nature of symmetry breaking. The physics of T violation is often linked, via the CPT theorem, to the violation of the combined Charge conjugate (C) and P symmetry. The only confirmed source of CP violation in the SM is the complex phase of the CKM matrix (that describes the quark mixing in charged-current weak interactions). With it, the electron EDM (eEDM) manifests through high-order loop couplings that involve flavor-changing quark interactions with the exchange of W ± weak bosons. The resulting size of eEDM predicted within the framework of SM is no larger than 10 −38 e·cm, which is well beyond the reach of current experimental techniques. The current experimental upper bound is established using thallium atomic beams with a sensitivity of 1.6×10 −27 e·cm [4]. New sources of CP violation introduced by theories beyond
121822416
Beta decay measurements with ultracold neutrons: a review of recent measurements and the research program at Los Alamos National Laboratory
We present a review of the motivation and results of recent experiments which utilize ultracold neutrons for measurements of neutron beta decay. Because these experiments hinge critically on the available ultracold neutron source technology, we also review the status of ultracold neutron source development, emphasizing the Los Alamos ultracold neutron facility and the ongoing beta decay research program sited there.
14238961
Quark Mass Hierarchy and CP Violation in Low Energy Supersymmetry
A pattern of quark mass hierarchy and CP violation within the framework of low energy supersymmetry is described. By assuming some discrete symmetry among the three families, the quarks of the third family obtain masses at tree level. The second family obtains masses radiatively at one-loop level due to the soft breaking of the family symmetry. At this level, the first family remains massless by some degeneracy conditions of the squarks. As a result of R parity violation, the sneutrino vacuum expectation values are nonvanishing. CP violation occurs through the superweak sneutrino exchange. This picture is consistent with the experiments on the flavor-changing neutral current.
13218409
Electroweak symmetry breaking due to confinement
Within the framework of gauge mediated supersymmetry breaking, we consider an electroweak symmetry breaking pattern in which there is no conventional Cl term. The pattern is made appealing through realizing it as low energy effective description of a supersymmetric Yang-Mills theory which is of confinement. Phenomenological implications are discussed.
116033320
Search for CP violation in B0s to Jpsi Phi
The CDF experiment, which uses p{bar p} collisions at {radical}s = 1.9 TeV produced at the Fermilab Tevatron, is unique in its ability to observe all flavors of B hadrons and measure their properties. Among them, CP violation is of fundamental interest. In the B{sup +} and B{sup 0} systems, measurements of CP violation parameters performed essentially at B factories have borne out the predictions of CKM model. Little is known, experimentally, about CP violation in the B{sub s}{sup 0} system. The standard model predicts very little CP violation there, thus any nonzero measurement could be an indication of new physics. In this thesis, we will report on the very first flavor-tagged analysis of approximately 2000 B{sub s}{sup 0} {yields} J/{psi}{phi} decays reconstructed in a 1.35 fb{sup -1} data sample collected at CDF. This channel is sensitive not only to the width difference {Delta}{Lambda} in the B{sub s}{sup 0} system but also to the CP violation parameter {beta}{sub s}. The final result we obtain is a confidence region in the two dimensional space of {beta}{sub s} and {Delta}{Lambda}. Assuming the standard model predictions of {beta}{sub s} and {Delta}{Lambda}, the probability is 15%, corresponding to 1.5 Gaussian standard deviations.
115174219
D-branes and Azumaya noncommutative geometry: From Polchinski to Grothendieck
In this continuation of (L-Y3) (arXiv:0709.1515 (math.AG)), (L-L-S-Y) (arXiv:0809.2121 (math.AG)), (L-Y4) (arXiv:0901.0342 (math.AG)), (L-Y5) (arXiv:0907.0268 (math.AG)), and (L-Y6) (arXiv:0909.2291 (math.AG)), we give an overview of the posted part of the project and then take it as background to introduce Azumaya noncommutative C ∞ -manifold and the four aspects of morphisms therefrom to a projective complex manifold. This gives us then a description of supersymmetric D-branes of A-type in a Calabi-Yau manifold along the line of the Polchinski-Grothendieck Ansatz. The notion of Kahler differentials and their tensors for an Azumaya noncommutative space are introduced. Donaldson's picture of Lagrangian and special Lagrangian submanifolds as selected from the zero-locus of a moment-map on a related space of maps can be merged into the setting of morphisms from Azumaya man- ifolds with a fundamental module. As a pedagogical toy model for illustration, we study D-branes of A-type in a Calabi-Yau torus. Simple as it is, it reveals already several features of D-branes of A-type, including their assembling/disassembling. The short-vs.-long string wrapping behavior of matrix-strings in the string-theory literature can be produced in this context as well. In addition to the previous comparison with stringy works made, the 4th theme (subtitled: "Gomez-Sharpe vs. Polchinski-Grothendieck") of Sec. 2.4 is to be read with the work (G-Sh) (arXiv:hep-th/0008150), while the 2nd theme (subtitled: "Donagi- Katz-Sharpe vs. Polchinski-Grothendieck") of Sec. 4.2 is to be read with the work (D-K-S) (arXiv:hep-th/0309270). Sec. 4.3, though not yet ready to be subtitled "Denef vs. Polchinski- Grothendieck", is to be read with the work (De) (arXiv:hep-th/0107152). Some directly related string-theory remarks are added to the end of each section.
14127649
Recent Lifetime and Mixing Measurements at the Tevatron
We present the latest $B$ hadron lifetimes, $B^0_s$ mixing, and $D^0$ mixing measurements using up to 3.0 fb$^{-1}$ of data collected by CDF and D0 experiments at Fermilab. The $B^0_s$ lifetime is measured from both $J/\psi \phi$ (CP admixture) and flavor specific channels, and the $B_c$ lifetime is obtained from semileptonic channels. Following the $B^0_s$ oscillation frequency measurement at CDF in 2006, the D0 collaboration now observes $B^0_s$ oscillation at a significance of about 3$\sigma$. Since the first $D^0$ mixing evidence established at $B$ factories in 2007, CDF has observed $D^0$ mixing at a significance of about 4$\sigma$ level, the first time from hadron collider.