31299789
Electron cooling of high-energy protons in a multiring trap with a tank circuit monitoring the electron-plasma oscillations.
Electron cooling of energetic protons in a multiring trap was investigated experimentally with a tank circuit monitoring electron-plasma oscillations in the trap. The energy of protons was determined by time-of-flight measurements. It is found that a simple model can explain the qualitative behavior of both electron and proton energy when the initial energy of protons is less than 2 keV. Monitoring the electron-plasma temperature with a tank circuit can be an effective tool when energetic particles are electron cooled in a multiring trap.
14918025
Water abundance in molecular cloud cores
We present Submillimeter Wave Astronomy Satellite (SWAS) observations of the 110 → 101 transition of ortho-H2O at 557 GHz toward 12 molecular cloud cores. The water emission was detected in NGC 7538, ρ Oph A, NGC 2024, CRL 2591, W3, W3OH, Mon R2, and W33 and was not detected in TMC-1, L134N, and B335. We also present a small map of the H2O emission in S140. Observations of the H218O line were obtained toward S140 and NGC 7538, but no emission was detected. The abundance of ortho-H2O relative to H2 in the giant molecular cloud cores was found to vary between 6 × 10-10 and 1 × 10-8. Five of the cloud cores in our sample have previous H2O detections; however, in all cases the emission is thought to arise from hot cores with small angular extents. The H2O abundance estimated for the hot core gas is at least 100 times larger than in the gas probed by SWAS. The most stringent upper limit on the ortho-H2O abundance in dark clouds is provided in TMC-1, where the 3 σ upper limit on the ortho-H2O fractional abundance is 7 × 10-8.
119232297
Subaru Constraint on Circular Polarization in I-Band Emission from the Magnetar 4U 0142+61
We present the first imaging circular polarimetry of the anomalous X-ray pulsar (AXP) 4U 0142+61 at optical wavelengths. The AXP is the only magnetar that has been well studied at optical and infrared wavelengths, and is known to have a complicated broad-band spectrum over the wavelength range. The optical polarimetric observation was carried out with the 8.2-m Subaru telescope at the I-band. From the observation, the degree of circular polarization, V, was measured to be V = 1.1 +/- 2.0%, or vertical bar V vertical bar <= 4.3% (90% confidence). The relatively large uncertainty was due to the faintness of the source (I = 23.4-24.0). Considering the currently suggested models for optical emission from magnetars, our result is not sufficiently conclusive to discriminate the models. We suggest that because linear polarization is expected to be strong in the models, linear polarimetry of this magnetar should be conducted.
119266949
MULTIBAND STUDIES OF THE OPTICAL PERIODIC MODULATION IN THE X-RAY BINARY SAX J1808.4–3658 DURING ITS QUIESCENCE AND 2008 OUTBURST
We report on time-resolved optical imaging of the X-ray binary SAX J1808.4-3658 during its quiescent state and 2008 outburst. The binary, containing an accretion-powered millisecond pulsar, has a large sinusoidal-like modulation in its quiescent optical emission. We employ a Markov chain Monte Carlo technique to fit our multi-band light curve data in quiescence with an irradiated star model, and derive a tight constraint of 50(-5)(+6) deg on the inclination angle i of the binary system. The pulsar and its companion are constrained to have masses of 0.97(-0.22)(+0.31) M-circle dot and 0.04(-0.01)(+0.02) M-circle dot (both 1 sigma ranges), respectively. The dependence of these results on the measurements of the companion's projected radial velocity is discussed. We also find that the accretion disk had nearly constant optical fluxes over a similar to 500 day period in the quiescent state our data covered, but started brightening 1.5 months before the 2008 outburst. Variations in modulation during the outburst were detected in our four observations made 7-12 days after the start of the outburst, and a sinusoidal-like modulation with 0.2 mag amplitude changed to have a smaller amplitude of 0.1 mag. The modulation variations are discussed. We estimate the albedo of the companion during its quiescence and the outburst, which was approximately 0 and 0.8 (for isotropic emission), respectively. This large difference probably provides additional evidence that the neutron star in the binary turns on as a radio pulsar in quiescence.
119922132
Transport beam line for ultraslow monoenergetic antiprotons
A beam line for the transportation of slow antiprotons from a multiring electrode trap to an experimental chamber is described. The beam line is equipped with a three-stage differential pumping system in order to maintain a pressure lower than 1×10−12 Torr in the trap region while simultaneously having a pressure of around 1×10−6 Torr in the chamber. Tests have shown that 105 positive ions per trapping cycle were successfully extracted at 250 eV from the trap positioned in a superconducting solenoid. The ions were then further transported through three small apertures to the target area located 3.5 m downstream of the trap. Results from the first delivery of a 250 eV antiproton beam are described.
119397253
Evidence for superdeformation in Dy-149,Dy-150: Onset of the collapse of the Z=66 deformed shell closure?
An experiment has been performed to search for superdeformed (SD) states in Dy-149,Dy-150. While no evidence for discrete superdeformed states has been observed, a superdeformed ridge with a separation of Delta E-gamma=52 keV with a total intensity of 1.8+/-0.5% that of Dy-150 has been observed. An upper limit of 0.8% (0.9%), of the intensity of Dy-150 (Dy-149), is placed for observation of the most intense discrete line states. The relative weakness in the SD population is suggested to be due to a rapid decrease in the depth of the superdeformed minimum, as one moves away from doubly magic Dy-152.
118927955
Inelastic Scatterings of Entangled Mossbauer Gammas
We report the observation of the temperature-dependent inelastic scattering of three entangled Mossbauer gammas in the time-resolved Mossbauer spectroscopy. Recently, the long-lived E3 Mossbauer transition of rhodium generated by bremsstrahlung irradiation has been reported. Two kinds of X-rays with the fast decay are attributed to the tri-photon effect. They are tri-photon pile-up of rhodium K X-rays and the high-Z impurity K X-rays. Energy of the particular K emission is higher than the sum energy of two Mossbauer gammas. This letter reports new discoveries by cooling down the sample using liquid nitrogen, namely the collective anomalous emission of entangled Mossbauer gammas. The enhancement of inelastic scatterings at low temperature such as rhodium K satellites is attributed to this entanglement.
118521941
Relativistic quantum effects of Dirac particles simulated by ultracold atoms
Quantum simulation is a powerful tool to study a variety of problems in physics, ranging from high-energy physics to condensed-matter physics. In this article, we review the recent theoretical and experimental progress in quantum simulation of Dirac equation with tunable parameters by using ultracold neutral atoms trapped in optical lattices or subject to light-induced synthetic gauge fields. The effective theories for the quasiparticles become relativistic under certain conditions in these systems, making them ideal platforms for studying the exotic relativistic effects. We focus on the realization of one, two, and three dimensional Dirac equations as well as the detection of some relativistic effects, including particularly the well-known Zitterbewegung effect and Klein tunneling. The realization of quantum anomalous Hall effects is also briefly discussed.
4372235
A debris disk around an isolated young neutron star
Pulsars are rotating, magnetized neutron stars that are born in supernova explosions following the collapse of the cores of massive stars. If some of the explosion ejecta fails to escape, it may fall back onto the neutron star or it may possess sufficient angular momentum to form a disk. Such ‘fallback’ is both a general prediction of current supernova models and, if the material pushes the neutron star over its stability limit, a possible mode of black hole formation. Fallback disks could dramatically affect the early evolution of pulsars, yet there are few observational constraints on whether significant fallback occurs or even the actual existence of such disks. Here we report the discovery of mid-infrared emission from a cool disk around an isolated young X-ray pulsar. The disk does not power the pulsar's X-ray emission but is passively illuminated by these X-rays. The estimated mass of the disk is of the order of 10 Earth masses, and its lifetime (≥ 106 years) significantly exceeds the spin-down age of the pulsar, supporting a supernova fallback origin. The disk resembles protoplanetary disks seen around ordinary young stars, suggesting the possibility of planet formation around young neutron stars.
54803118
Analysis of the scalar doubly heavy tetraquark states with QCD sum rules
In this article, we perform a detailed study of the mass spectrum of the scalar doubly charmed and doubly bottom tetraquark states using the QCD sum rules.
7625841
Topological Hamiltonian as an exact tool for topological invariants.
We propose the concept of 'topological Hamiltonian' for topological insulators and superconductors in interacting systems. The eigenvalues of the topological Hamiltonian are significantly different from the physical energy spectra, but we show that the topological Hamiltonian contains the information of gapless surface states, therefore it is an exact tool for topological invariants.