Muonic helium atom hyperfine structure (HFS) measurements are a sensitive tool to test the three-body atomic system and bound-state quantum electrodynamics theory, and determine fundamental constants ...of the negative muon magnetic moment and mass. The world's most intense pulsed negative muon beam at the Muon Science Facility of the Japan Proton Accelerator Research Complex allows improvement of previous measurements and testing further CPT invariance by comparing the magnetic moments and masses of positive and negative muons (second-generation leptons). We report new ground-state HFS measurements of muonic helium-4 atoms at a near-zero magnetic field, performed for the first time using a small admixture of CH_{4} as an electron donor to form neutral muonic helium atoms efficiently. Our analysis gives Δν=4464.980(20) MHz (4.5 ppm), which is more precise than both previous measurements at weak and high fields. The muonium ground-state HFS was also measured under the same conditions to investigate the isotopic effect on the frequency shift due to the gas density dependence in He with CH_{4} admixture and compared with previous studies. Muonium and muonic helium can be regarded as light and heavy hydrogen isotopes with an isotopic mass ratio of 36. No isotopic effect was observed within the current experimental precision.
Antihydrogen, a positron bound to an antiproton, is the simplest antiatom. Its counterpart-hydrogen--is one of the most precisely investigated and best understood systems in physics research. ...High-resolution comparisons of both systems provide sensitive tests of CPT symmetry, which is the most fundamental symmetry in the Standard Model of elementary particle physics. Any measured difference would point to CPT violation and thus to new physics. Here we report the development of an antihydrogen source using a cusp trap for in-flight spectroscopy. A total of 80 antihydrogen atoms are unambiguously detected 2.7 m downstream of the production region, where perturbing residual magnetic fields are small. This is a major step towards precision spectroscopy of the ground-state hyperfine splitting of antihydrogen using Rabi-like beam spectroscopy.
We report here the first successful synthesis of cold antihydrogen atoms employing a cusp trap, which consists of a superconducting anti-Helmholtz coil and a stack of multiple ring electrodes. This ...success opens a new path to make a stringent test of the CPT symmetry via high precision microwave spectroscopy of ground-state hyperfine transitions of antihydrogen atoms.
A new class of zero-correlation zone sequences Torii, H.; Nakamura, M.; Suehiro, N.
IEEE transactions on information theory,
2004-March, 2004-03-00, 20040301, Volume:
50, Issue:
3
Journal Article
Peer reviewed
In this correspondence, two new methods for constructing sets of zero-correlation zone (ZCZ) sequences are proposed. These methods are based on perfect sequences and unitary matrices. Compared with ...previous methods, the proposed methods can generate sets of nonbinary ZCZ sequences having a longer zero-correlation zone. The sequences obtained by these methods are suitable for approximately synchronized code-division multiple-access (AS-CDMA) systems.
Abstract
Measurements of the muonic helium atom hyperfine structure (HFS) are a sensitive tool to test the theory of three-body atomic systems and bound-state quantum electrodynamics (QED) and to ...determine fundamental constants of the negative muon magnetic moment and mass. The world’s most intense pulsed negative muon beam at J-PARC MUSE brings an opportunity to improve previous measurements and test further CPT invariance by comparing the magnetic moments and masses of positive and negative muons. Test measurements at D-line are now in progress utilizing MuSEUM apparatus at zero field. The first results already have better accuracy than previous measurements in the 1980s. Also, the investigation of a new experimental approach to improve HFS measurements by repolarizing muonic helium atoms using a spin-exchange optical pumping (SEOP) technique was started. If successful, this would drastically improve the measurement accuracy.
Abstract
At J-PARC, the MuSEUM (Muonium Spectroscopy Experiment Using Microwave) collaboration aims to precisely measure the ground-state hyperfine splitting of muonium atoms arising from the muon ...and electron spins. The pulsed muon beam is stopped in a krypton gas cell to form muonium atoms. The transitions of spin states are induced with a microwave cavity, which are then measured by positron counters. After the previously performed successful measurements with a nearly-zero magnetic field, we are currently planning a measurement with the 2.9T magnetic field by measuring two Zeeman-split sub-levels, so that increased statistics will allow us to more precisely determine the transition frequency down to ∼1ppb. Moreover, a new microwave cavity with a unique geometry is being designed to perform the measurement at an even stronger field of 2.9T in the future.
We have used a radio frequency quadrupole decelerator to decelerate antiprotons emerging from the CERN Antiproton Decelerator from MeV- to keV-scale energy, and collected five decelerated pulses in a ...multiring trap. Some 5 x 10(6) antiprotons were stacked in this way. Cooling of the trapped antiprotons by a simultaneously trapped electron plasma was studied nondestructively via shifts in plasma mode frequencies. We have also demonstrated the first step in extracting a 10-500 eV antiproton beam from the trap.
The frequency shift of the center-of-mass oscillation, known as the (1,0) mode, of a trapped electron plasma and, furthermore, its time evolution were observed during the cooling of an injected ...antiproton beam for the first time. Here, antiprotons mixed with the electrons did not follow faster electron oscillations but contributed to the modification of the effective potential. The time evolution of the plasma temperature, deduced from the frequency shift of the excited (3,0) mode, suggested that there was an abnormal energy deposition of the antiproton beam in the electron plasma before thermalization.
Direct detection of antihydrogen atoms using a BGO crystal Nagata, Y.; Kuroda, N.; Ohtsuka, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2016, Volume:
840
Journal Article
Peer reviewed
The ASACUSA collaboration has developed a detector consisting of a large size BGO crystal to detect an atomic antihydrogen beam, and performed the direct detection of antihydrogen atoms. Energy ...spectra from antihydrogen annihilation on the BGO crystal are discussed in comparison to simulation results from the GEANT4 toolkit. Background mainly originating from cosmic rays were strongly suppressed by analyzing the energy deposited in the BGO and requiring a multiplicity of charged pions. Thus antihydrogen events were identified.
Background
Facial psoriasis was reported in 17–68% of patients with psoriasis and shown to have a negative impact on patients’ personal and health‐related quality of life (HRQoL).
Objectives
To ...explore the association of facial psoriasis with patients’ HRQoL and to assess the relationship between ixekizumab (IXE) and improvement in facial psoriasis and changes in HRQoL.
Methods
This work reports the combined results of two phase III multicentre, randomized, double‐blind, placebo‐controlled, active‐comparator trials in patients with moderate‐to‐severe psoriasis. Patients received placebo, etanercept (ETN; 50 mg twice weekly) or IXE 80 mg every 4 weeks (Q4W) or every 2 weeks (Q2W) for up to 12 weeks following an initial 160‐mg dose. HRQoL parameters were analysed based on facial psoriasis status at baseline using analysis of covariance models. Improvement was assessed as percentage of patients with no facial psoriasis.
Results
The combined database included 1133 patients with facial psoriasis and 1437 without. Patients treated with IXE whose facial psoriasis cleared had improved Dermatology Life Quality Index 0.1 responses (P < 0.01) compared with patients with facial psoriasis at Week 12. At Week 12, clearance of facial psoriasis compared with the presence of facial psoriasis was independently associated with significantly better improvement in Psoriasis Skin Appearance Bothersomeness scores in the IXE Q2W treatment group (P < 0.01). At Week 12, facial clearance and overall Psoriasis Area Severity Index (PASI) improvement were observed in significant numbers of patients treated with IXE compared with ETN and placebo. Facial psoriasis clearance at Week 12 in patients treated with IXE or ETN was positively associated with PASI75 and PASI90 achievement.
Conclusion
Facial psoriasis had a larger negative impact on HRQoL than no facial psoriasis. Facial psoriasis clearance was associated with improved HRQoL. Significantly more IXE‐treated patients had rapid facial clearance vs. ETN and PBO, which led to better clinical outcomes.
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