Extremely low vertical-emittance beam in the accelerator test facility at KEK

Electron beams with the lowest, normalized transverse emittance recorded so far were produced and confirmed in single-bunch-mode operation of the Accelerator Test Facility at KEK. We established a tuning method of the damping ring which achieves a small vertical dispersion and small x-y orbit coupling. The vertical emittance was less than 1% of the horizontal emittance. At the zero-intensity limit, the vertical normalized emittance was less than 2.8 x 10(-8) rad m at beam energy 1.3 GeV. At high intensity, strong effects of intrabeam scattering were observed, which had been expected in view of the extremely high particle density due to the small transverse emittance.     

Propagation of a beam halo in accelerator test facility 2 at KEK

The beam halo is a major issue for interaction region (IR) backgrounds at many colliders, for example, future linear colliders, B factories, and also it is an important problem at ATF2. In this paper, we report on the halo propagation along the ATF2 beam line with realistic apertures, the nonlinear optics influence on the increasing number of halo particles input is analyzed, and the transmitted halo particles distribution just before the last BPM is then described, the results from which will benefit the Compton recoil electrons measurement.     

Surface-roughness wakefield measurements at brookhaven accelerator test facility

An experiment has been carried out at the Brookhaven Accelerator Test Facility to investigate the effect of a surface-roughness wakefield in narrow beam tubes with artificially created bumps. The measurements show that the synchronous modes decay significantly due to the randomization of the roughness pattern. It is pointed out that this decay mechanism has not been investigated in the previous experiment at DESY and the investigators' conclusion does not apply for surface-roughness wakefields in real surfaces.     

Nuclear Resonant scattering experiments with synchrotron radiation at KEK

Experiments of nuclear Resonant scattering carried out at PF and TRISTAN-AR of KEK are described, which include nuclear Bragg scattering in time domain as well as energy domain, time-resolved nuclear resonant forward scattering, and interferometric studies.     

High-pressure x-ray diffraction station at the beijing synchrotron radiation facility

Abstract

In the second phase construction of further insertion devices, beamlines and experimental stations at the Beijing Synchrotron Radiation Facility, a dedicated high-pressure x-ray diffraction station will be constructed. We outline the synchrotron radiation source, beamline optics and high-pressure x-ray diffraction apparatus. This facility is planned to operate for users in 1994.

Presented at the IUCr Workshop on ‘Synchrotron Radiation Instrumentation for High Pressure Crystallography’, Daresbury Laboratory 20-21 July 1991     

Folded tandem ion accelerator facility at trombay

The folded tandem ion accelerator (FOTIA) project at BARC has been commissioned. The analysed carbon beams of 40 nA(3⁺) and 25 nA(4⁺), at terminal voltage of 2.5 MV with N₂ + CO₂ as insulating gas, were obtained. The beams were characterized by performing the Rutherford back scattering (RBS) on gold, tin and iron targets. The beam energy of 12.5 MeV for ¹²C⁴⁺ was consistent with the terminal voltage of 2.5 MV. The N₂ + CO₂ mixture is being replaced by SF₆ gas in order to achieve 6 MV on the terminal. In this paper, some of the salient features of the FOTIA and its present status are discussed.     

Experimental observation of optical diffraction radiation

The optical diffraction radiation of ultrarelativistic electrons at the boundary of a conducting medium is observed experimentally. Backward diffraction radiation, which, like transition radiation, is emitted at the angle of specular reflection from the target, is detected. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 10, 760–764 (25 May 1998)     

The liquid-lithium target at the soreq applied research accelerator facility

The European Physical Journal A - In stars, the fusion of $$^{22}$$ Ne and $$^4$$ He may produce either $$^{25}$$ Mg, with the emission of a neutron, or $$^{26}$$ Mg and a $$\gamma $$ ray. At high...     

Non-Liouvillian carbon nucleus accumulation at the ITEP storage accelerator facility

Physical start-up of the new heavy-ion storage accelerator facility has been successfully performed at the Institute of Theoretical and Experimental Physics. Carbon nuclei with an energy of 200 MeV/n are accumulated in the storage ring of the 10-GeV U-10 proton synchrotron, which is converted into an ion accumulator. The accumulation is accomplished using solid-target charge exchange of C⁴⁺ ions that are accelerated in the UK booster synchrotron. Thus, non-Liouvillian carbon nucleus accumulation is accomplished experimentally. Our immediate goal is to raise the amount of accumulated nuclei to 2 × 10¹², which corresponds to the possibilities of the available facility configuration.     

Energy measurement at the Darmstadt unilac accelerator

The kinetic energy of⁸⁶Kr ions accelerated by UNILAC (GSI-Darmstadt) was measured using the recoil proton technique. A good agreement was found with the energy values obtained by the time-of-flight technique currently used at UNILAC.     

Achievement of ultralow emittance beam in the accelerator test facility damping ring

For high luminosity in electron-positron linear colliders, it is essential to generate low vertical emittance beams. We report on the smallest vertical emittance achieved in single-bunch-mode operation of the Accelerator Test Facility, which satisfies the requirement of the x-band linear collider. The emittances were measured with a laser-wire beam-profile monitor installed in the damping ring. The bunch length and the momentum spread of the beam were also recorded under the same conditions. The smallest vertical rms emittance measured at low intensity is 4 pm at a beam energy of 1.3 GeV, which corresponds to the normalized emittance of 1.0x1.0(-8) m. It increases by a factor of 1.5 for a bunch intensity of 10(10) electrons. The measured data agreed to the calculation of intrabeam scattering within much better than a factor of 2.     

Feasibility of low-energy radiative-capture experiments at the LUNA underground accelerator facility

The LUNA (Laboratory Underground for Nuclear Astrophysics) facility has been designed to study nuclear reactions of astrophysical interest. It is located deep underground in the Gran Sasso National Laboratory, Italy. Two electrostatic accelerators, with 50 and 400 kV maximum voltage, in combination with solid and gas target setups allowed to measure the total cross-sections of the radiative-capture reactions ^2H²H(p, )^3He³Heand ^14N¹⁴N(p, )^15O¹⁵Owithin their relevant Gamow peaks. We report on the gamma background in the Gran Sasso laboratory measured by germanium and bismuth germanate detectors, with and without an incident proton beam. A method to localize the sources of beam-induced background using the Doppler shift of emitted gamma rays is presented. The feasibility of radiative-capture studies at energies of astrophysical interest is discussed for several experimental scenarios.     

A beam test of prototype time projection chamber using micro-pattern gas detectors at KEK

We conducted a series of beam tests of prototype TPCs for the international linear collider (ILC) experiment, equipped with an MWPC, a MicroMEGAS, or GEMs as a readout device. The prototype operated successfully in a test beam at KEK under an axial magnetic field of up to 1 T. The analysis of data is now in progress and some of the preliminary results obtained with GEMs and MicroMEGAS are presented along with our interpretation. Also given is the extrapolation of the obtained spatial resolution to that of a large TPC expected as the central tracker of the ILC experiment. on behalf of part of the ILC-TPC Collaboration     

The TITAN mass measurement facility at TRIUMF-ISAC

The TITAN facility at TRIUMF-ISAC will use four ion traps with the primary goal of determining nuclear masses with high precision, particularly for short lived isotopes with lifetimes down to approximately 10 ms. The design value for the accuracy of the mass measurement is 1 ×10^???8. The four main components in the facility are an RF cooler/buncher (RFCT) receiving the incoming ion beam, an electron beam ion trap (EBIT) to breed the ions to higher charge states, a cooler Penning trap (CPET) to cool the highly charged ions, and finally the measurement Penning trap (MPET) for the precision mass determination. Additional goals for this system are laser spectroscopy on ions extracted from the RFCT and beta spectroscopy in the EBIT (in Penning trap mode) on ions that are purified using selective buffer gas cooling in the CPET. The physics motivation for the mass measurements are manifold, from unitarity tests of the CKM matrix to nuclear structure very far from the valley of stability, nuclear astrophysics and the study of halo-nuclei. As a first measurement the mass of ¹¹Li will be determined. With a lifetime of 8.7 ms and a demonstrated production rate of 4×10⁴ ions/sec at ISAC the goal for this measurement at TITAN is a relative uncertainty of 5×10^???8. This would check previous conflicting measurements and provide information for nuclear theory and models.     

Transition radiation detector for relativistic particles at accelerator energies

Transition radiation (TR) has been investigated by using the arithmetic mean and the geometric mean of the pulses from 10 multiwire proportional chambers. The discrimination factor for different kinds of particles has been determined. Also the dependence of the intensity of TR on the Lorentz factor γ has been measured and compared with theoretical calculations.     

The compressed baryonic matter experiment at the future accelerator facility FAIR in Darmstadt

At the future Facility for Antiproton and Ion Research (FAIR) in Darmstadt a dedicated heavy-ion experiment investigating the properties of highly compressed baryonic matter (CBM) is proposed. Its goal will be to explore the QCD phase diagram in the region of moderate temperatures but very high baryon densities. Physics observables of interest, the experimental challenge of measuring them and first feasibility studies on charm production will be discussed.     

The LUE-200 accelerator at the IREN facility: Current status and development

The general scheme and current status of an electron linear accelerator with an S-band travelling wave (f = 2856 MHz) accelerating structure—a driver for a pulsed neutron source (the Intense Resonance Neutron source (IREN)) at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research—are presented. The parameters of the accelerating system and the measured parameters of the electron beam—pulse-beam current, duration of the current pulse, repetition rate, electron-energy spectrum, and loading characteristics of the accelerating structure—are given. The beginning of the implementation of the project of the second stage of the IREN facility, which forms the basis for the development of the accelerator aimed at increasing its beam power, is reported. Technical solutions underlying the modernization of the accelerator’s electrophysical systems are discussed: accelerating system, RF power supplies, and modulators.