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.
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.
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.
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
5304169
A high dynamic range data acquisition system for a solid-state electron electric dipole moment experiment.
We have built a high precision (24-bit) data acquisition (DAQ) system capable of simultaneously sampling eight input channels for the measurement of the electric dipole moment of the electron. The DAQ system consists of two main components: a master board for DAQ control and eight individual analog-to-digital converter (ADC) boards for signal processing. This custom DAQ system provides galvanic isolation of the ADC boards from each other and the master board using fiber optic communication to reduce the possibility of ground loop pickup and attain ultimate low levels of channel cross-talk. In this paper, we describe the implementation of the DAQ system and scrutinize its performance.
14087435
Determination of the Free Neutron Lifetime
We present the status of current US experimental efforts to measure the lifetime of the free neutron by the "beam" and "bottle" methods. BBN nucleosynthesis models require accurate measurements with 1 second uncertainties, which are currently feasible. For tests of physics beyond the standard model, future efforts will need to achieve uncertainties well below 1 second. We outline paths achieve both.
16041460
Intermediate scale dependence of non-universal gaugino masses in supersymmetric SO(10)
We calculate the dependence on the intermediate scale of the gaugino mass ratios upon breaking of SO(10) into the standard model via an intermediate group H. We see that the ratios change significantly when the intermediate scale is low (say, 10(8) GeV or 1 TeV) compared to the case when the two breakings occur at the same scale.
54868722
EXPERIMENTAL PROGRESS OF DC-SC PHOTOINJECTOR AT PEKING UNIVERSITY*
Beam loading experiments on DC-SC photoinjector test facility have been finished at 4.4 K. Upon the present experiments, the gradient of 6 MV/m is achieved. The maximum energy gain is 1.1 MeV at 4.4 K. With average beam current of 270 mA, the measured rms emittance is about 5 mm-mrad at the beam energy of 500 keV. Experiments on the test facility has validated that the DC-SC photoinjector is a good choice to provide moderate average current electron beams with low bunch charge and very high repetition rate.
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.
341730
Target-space duality between simple compact Lie groups and Lie algebras under the Hamiltonian formalism: I. Remnants of duality at the classical level
AbstractIt has been suggested that a possible classical remnant of the phenomenon of target-space duality (T-duality) would be the equivalence of the classical string Hamiltonian systems. Given a simple compact Lie groupG with a bi-invariant metric and a generating function Γ suggested in the physics literature, we follow the above line of thought and work out the canonical transformation Φ generated by Γ together with an Ad-invariant metric and a B-field on the associated Lie algebra
$$\mathfrak{g}$$
 ofG so thatG and
$$\mathfrak{g}$$
 form a string target-space dual pair at the classical level under the Hamiltonian formalism. In this article, some general features of this Hamiltonian setting are discussed. We study properties of the canonical transformation Φ including a careful analysis of its domain and image. The geometry of the T-dual structure on
$$\mathfrak{g}$$
 is lightly touched. We leave the task of tracing back the Hamiltonian formalism at the quantum level to the sequel of this paper.
15925356
A heavy Higgs particle in the TeV mass range
Abstract The first simulation results are presented on Higgs mass calculations in the spontaneously broken phase of the Higgs sector in the minimal Standard Model with higher derivative regulator. A heavy Higgs particle is found in the TeV mass range in the presence of a complex conjugate ghost pair at higher energies. The ghost pair evades easy experimental detection and a nonperturbative reinterpretation of the triviality Higgs mass bound becomes necessary.