Measurement of the neutron lifetime in a magnetic storage ring

In previous papers a storage ring for neutrons was reported, which enables the confinement of very slow neutrons by means of their magnetic moment in a magnetic multipole torus. Improved experimental conditions permitted to determine the life-time of the stored neutrons by measuring their number with good accuracy up to one hour. After an initial phase the decrease with time follows very well a single exponential function with a time constant τ=877±10s. As explained in the paper this number represents the lifetime of the free neutron within the given errors.     

合肥储存环电子束流寿命分析

 电子束流寿命是个很重要的指标,直接影响合肥光源的正常运行,为此研究了影响束流寿命的因素,测量了高频腔压、耦合度以及束团长度对电子束流寿命的影响,研究显示合肥储存环的电子束流真空寿命和托歇克寿命相当;并且利用束损系统测量了因托歇克寿命的变化而造成束流损失的相对变化;通过增加耦合度增加束流的垂直发射度,有效地提高了束流的寿命,保证了合肥光源的正常运行。     

合肥储存环电子束流寿命分析

电子束流寿命是个很重要的指标,直接影响合肥光源的正常运行,为此研究了影响束流寿命的因素,测量了高频腔压、耦合度以及束团长度对电子束流寿命的影响,研究显示合肥储存环的电子束流真空寿命和托歇克寿命相当;并且利用束损系统测量了因托歇克寿命的变化而造成束流损失的相对变化;通过增加耦合度增加束流的垂直发射度,有效地提高了束流的寿命,保证了合肥光源的正常运行。     

Electrostatic ultra-low-energy antiproton recycling ring

There is a strong need to push forward developments in the storage and control of ultra-low-energy antiproton beams to enable important scientific research. To this end, a small electrostatic ring, and associated electrostatic acceleration section, is being designed and developed by the QUASAR group. The ring will be placed on the MUSASHI beamline at the CERN-AD. It will serve as a prototype for the future ultra-low energy storage ring (USR), to be integrated at the facility for low-energy antiproton and ion research (FLAIR) and will enable various components of the USR to be tested and optimised. A reaction microscope will be integrated in the ring to enable partial ionisation cross section measurements to be made. This small recycler ring will be unique due to its combination of size, electrostatic nature and energy and type of circulating particles (ca 3?C30 keV antiprotons). A short electrostatic accelerating section is also being developed, which will be placed between the beamline and the ring to accelerate the antiprotons from the trap extraction energy (typically 250 eV) to the final required (re-circulating) energy. The AD recycler project will be described, including ring design, accelerating injection section and the inclusion of a reaction microscope and the experiments it will enable.     

Measurement method of the antiproton gravitational mass using the single electron transistor

We propose a non-destructive method to measure the trajectory of a single antiproton in a drift tube using position sensors based on the single electron transistor. We show that this recently developed device has sufficient sensitivity to detect the electric field of a moving charged particle. Comparing the trajectories of antiprotons and H⁻ ions could allow a reliable determination of the gravitational mass of the antiproton. This revised version was published online in August 2006 with corrections to the Cover Date.     

Beam lifetime measurement and analysis in Indus-2 electron storage ring

In this paper, the beam lifetime measurement and its theoretical analysis are presented using measured vacuum pressure and applied radio frequency (RF) cavity voltage in Indus-2 electron storage ring at 2 GeV beam energy. Experimental studies of the effect of RF cavity voltage and bunched beam filling pattern on beam lifetime are also presented. An equation of stable beam current decay is evolved and this equation closely follows the observed beam current decay pattern. It shows that the beam is stable and the beam current decay is due to the beam–residual gas interaction (vacuum lifetime) and electron–electron interaction within a bunch (Touschek lifetime). The estimated vacuum, Touschek and total beam lifetimes from analytical formulations are also compared with the measured beam lifetime.     

Measurement of optics for the SSRF storage ring in commissioning

The Shanghai Synchrotron Radiation Facility (SSRF) is a low emittance third-generation synchrotron radiation light source. Some optics parameters of the storage ring were measured when commissioning. This report presents the common methods for measuring some optics parameters of the storage ring, including the betatron tune, beta function, chromaticity, natural chromaticity and dispersion. The results and analysis of measurement for the optics parameters are given here, which are indispensable for the orbit correction of the accelerator and the nonlinear optimization.     

Measurement of optics for the SSRF storage ring in commissioning

The Shanghai Synchrotron Radiation Facility (SSRF) is a low emittance third-generation synchrotron radiation light source. Some optics parameters of the storage ring were measured when commissioning. This report presents the common methods for measuring some optics parameters of the storage ring, including the betatron tune, beta function, chromaticity, natural chromaticity and dispersion. The results and analysis of measurement for the optics parameters are given here, which are indispensable for the orbit correction of the accelerator and the nonlinear optimization.     

Measurement of the Lambdab0 lifetime using semileptonic decays

We report a measurement of the Lambda(b)(0) lifetime using a sample corresponding to 1.3 fb(-1) of data collected by the D0 experiment in 2002-2006 during run II of the Fermilab Tevatron collider. The Lambda(b)(0) baryon is reconstructed via the decay Lambda(b)(0)-->micronuLambda(c)(+)X. Using 4437+/-329 signal candidates, we measure the Lambda(b)(0) lifetime to be tau(Lambda(b)(0))=1.290(-0.110)(+0.119)(stat)(-0.091)(+0.087)(syst) ps, which is among the most precise measurements in semileptonic Lambda(b)(0) decays. This result is in good agreement with the world average value.     

Measurement of the neutron lifetime using a proton trap

We report a new measurement of the neutron decay lifetime by the absolute counting of in-beam neutrons and their decay protons. Protons were confined in a quasi-Penning trap and counted with a silicon detector. The neutron beam fluence was measured by capture in a thin 6LiF foil detector with known absolute efficiency. The combination of these simultaneous measurements gives the neutron lifetime: tau(n)=(886.8+/-1.2[stat]+/-3.2[syst]) s. The systematic uncertainty is dominated by uncertainties in the mass of the 6LiF deposit and the 6Li(n,t) cross section. This is the most precise measurement of the neutron lifetime to date using an in-beam method.     

Lasing of middle-infrared free-election lasers using the storage ring NIJI-IV

We report for the first time to our knowledge the experimental realization of a storage ring free-electron laser (FEL) in the middle-infrared (MIR) region. A technique to adjust the optical cavity using higher harmonic FELs was developed for a fundamental FEL in the MIR region. The MIR FELs were oscillated in the wavelength region of 2475 to 2673 nm, and the relative linewidth was 5×10??. A quasi-monochromatic x-ray beam with an energy of 700 keV was generated using FEL Compton backscattering. We were able to realize a quasi-monochromatic x-ray beam, whose energy is difficult to generate even in advanced synchrotron radiation facilities.     

Measurement of the τ lifetime

Using the 3-prong decays of τ leptons observed at the CELLO detector at PETRA, the τ lifetime is determined to be 4.7(_?2.9^+3.9)×10^?13s.     

Measurement of the Bs(0) lifetime using semileptonic decays

We report a measurement of the Bs(0) lifetime in the semileptonic decay channel Bs(0) --> Ds- mu+ nuX (and its charge conjugate), using approximately 0.4 fb(-1) of data collected with the D0 detector during 2002-2004. Using 5176 reconstructed Ds- mu+ signal events, we have measured the Bs(0) lifetime to be tau(Bs(0))=1.398+/-0.044(stat)(-0.025)(+0.028)(syst) ps. This is the most precise measurement of the Bs(0) lifetime to date.     

Measurement of the lifetime of b-baryons

The average lifetime of weakly decaying b-baryons was studied using 3.6 million hadronic decays collected by the DELPHI detector at LEP. The measurement of the proper decay time distribution of secondary vertices was used on three complementary samples. The first sample consisted of events with a fully reconstructed and an opposite charge lepton, or an oppositely charged lepton pair accompanied by a . The other two samples were more inclusive, where b-baryon semileptonic decays were recognized by the presence of either a proton identified by the RICH detector or a and a lepton of charge opposite to that of the proton. The combined result was: Received: 19 February 1999 / Revised version: 6 April 1999 / Published online: 3 August 1999