First observation of a (1,0) mode frequency shift of an electron plasma at antiproton beam injection

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.

Synthesis of cold antihydrogen in a cusp trap

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.

Radial compression of an antiproton cloud for production of intense antiproton beams

We report here the radial compression of a large number of antiprotons ( approximately 5 x 10(5)) in a strong magnetic field under ultrahigh vacuum conditions by applying a rotating electric field. Compression without any resonant structures was demonstrated for a range of frequencies from the sideband frequency of 200 kHz to more than 1000 kHz. The radial compression achieved is a key technique for synthesizing and manipulating antihydrogen atoms and antiprotonic atoms.

Compact cryogenic system with mechanical cryocoolers for antihydrogen synthesis

We have developed a compact cryogenic system which cools a vacuum chamber housing multi-ring trap electrodes (MRTs) of an antihydrogen synthesis trap using mechanical cryocoolers to achieve background pressure less than 10(-12) Torr. The vacuum chamber and the cryocoolers are thermally connected by copper strips of 99.9999% in purity. All components are installed within a diametric gap between the MRT of phi108 mm and a magnet bore of phi160 mm. An adjusting mechanism is prepared to align the MRT axis to the magnet axis. The vacuum chamber was successfully cooled down to 4.0 K after 14 h of cooling with heat load of 0.8 W.

Confinement of a large number of antiprotons and production of an ultraslow antiproton beam

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.

New scheme for positron accumulation in ultrahigh vacuum

A new positron accumulation scheme compatible with ultrahigh vacuum conditions has been developed, which is realized by preparing a high density electron plasma as high as approximately 10(11) cm(-3) and an ion cloud as energy absorbers. The present accumulation rate normalized by the intensity of 22Na positron source is (3.6+/-0.3)x10(2)e(+)/s/mCi, which is more than one and a half orders of magnitude higher than other ultrahigh vacuum compatible schemes so far reported.

Radial compression of protons and H3+ ions in a multiring trap for the production of ultralow energy antiproton beams

Radial compression of a proton cloud was performed in a multiring trap which was designed to trap and cool a large number of antiprotons for the production of low-energy ( 10-1000 eV ) antiproton beams. The resonance frequency for the radial compression was almost constant from 3 x 10(5) to 3 x 10(6) protons. The collision process of the trapped protons was also investigated to estimate the energy of the protons inside the trap. This technique will be applied to the ASACUSA experiment at the antiproton decelerator, CERN, to extract ultraslow antiprotons with good emittance.

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.

Higher yielding isolation of kinsenoside in Anoectochilus and its antihyperliposis effect

A higher concentration of kinsenoside, 3-(R)-3-beta-D-glucopyranosyloxybutanolide (1), was detected in the crude drug Anoectochilusformosanus, and A. koshunensis by HPLC analysis. A methylation reaction occurred to give methyl ester (4) when the lactone ring of 1 was cleaved by silica gel catalysis using methanol containing solvent used in the purification step resulting in difficulty to purify 1. To avoid the cleavage reaction, a reversed-phase or silica gel column without methanol was used to give a high yield of 1. In an anti-hyperliposis assay using high-fat diet rats, 1 significantly reduced the weights of body and liver, and also decreased the triglyceride level in the liver compared to those of control rats. On the other hand, the epimer of 1, 3-(S)-3-beta-glucopyranosy-loxybutanolide (2), trivially named goodyeroside A, which was isolated from Goodyera species, had no effect for anti-hyperliposis. In aurothioglucose-induced obese mouse, 1 suppressed the body and liver weight increase, significantly ameliorated the triglyceride level in the liver, and also reduced the deposition of uterine fat-pads.

Dynamics of electron-plasma vortex in background vorticity distribution

Dynamics of a point vortex in interaction with a broad profile of background vorticity is studied experimentally by using an electron plasma. The observed motion of the vortex compares favorably with a recently proposed theoretical model [D. A. Schecter and D. H. E. Dubin, Phys. Rev. Lett. 83, 2191 (1999)]. Perturbations in the background distribution in the wake of the spiral orbit of the vortex amount to several tens of percent and are considered to be a major reason for deviations of the observation from the linear theoretical model.

High-performance liquid chromatographic system for the rapid purification of growth-hormone receptor in rabbit livers

A system consisting of high-performance affinity chromatography and size-exclusion chromatography has been developed for the rapid purification and isolation of relatively labile membrane proteins, such as growth-hormone receptor. The crude membrane sample containing growth-hormone receptor was obtained from rabbit livers by ultracentrifugation, followed by solubilization with Triton X-100. The sample was introduced into the high-performance affinity gel column through a large-volume loop injector. After removal of unretained proteins, the fraction containing the growth-hormone receptor was eluted with 6 M urea solution. The eluate from the affinity column passed directly into the size-exclusion gel column, where rapid desalting and separation from contaminants were achieved. The eluate was monitored by UV absorption at 280 nm and fractionated for the subsequent binding assay with 125I-labelled human growth hormone.