Electron-scattering Facility Research Articles

Electron Scattering for Exotic Nuclei

Electron scattering is known to be one of the key experimental tools to study detailed internal structures of atomic nuclei, though its application to production-hard short-lived nuclei was not possible to date. Due to advances in accelerator technologies with efficient production scheme of unstable nuclei, the world’s first electron-scattering facility for exotic nuclei has started its operation. Long-awaited structure studies of exotic nuclei by electron scattering will be soon realized.

The SCRIT Electron Scattering Facility Project at the RIKEN RI Beam Factory

The SCRIT Electron Scattering Facility Project at the RIKEN RI Beam Factory

High precision momentum calibration of the magnetic spectrometers at MAMI for hypernuclear binding energy determination

We propose a new method for absolute momentum calibration of magnetic spectrometers used in nuclear physics, using the time-of-flight (TOF) differences of pairs of particles with different masses. In cases where the flight path is not known, a calibration can be determined by using the TOF differences of two pair combinations of three particles. A Cherenkov detector, read out by a radio frequency photomultiplier tube, is considered as the high-resolution and highly stable TOF detector. By means of Monte Carlo simulations it is demonstrated that the magnetic spectrometers at the MAMI electron-scattering facility can be calibrated absolutely with an accuracy δp/p≤10−4, which will be crucial for high precision determination of hypernuclear masses.

Electron scattering for exotic nuclei

A brand-new electron scattering facility, the SCRIT Electron Scattering Facility, will soon start its operation at RIKEN RI Beam Factory, Japan. This is the world’s first electron scattering facility dedicated to the structure studies of short-lived nuclei. The goal of this facility is to determine the charge density distributions of short-lived exotic nuclei by elastic electron scattering. The first collision between electrons and exotic nuclei will be observed in the year 2014.

Nuclear physics at the SCRIT electron scattering facility

The SCRIT electron scattering facility is under construction at the RIKEN RI Beam Factory. This is the worlds first facility dedicated to the study of the structure of short-lived nuclei by electron scattering, which has been a long-standing dream for nuclear physics. A novel Self-Confining RI Target (SCRIT) technique makes this challenging research possible. A series of test experiments using stable nuclei performed at this partially completed facility show that the collision luminosity between electron beam and target nucleus reaches 10^27cm^-'2s^-'1, which is required for an elastic electron scattering measurement to determine the charge density distribution of the target nucleus. The first electron scattering for unstable Sn isotopes will take place in the year 2014. Nuclear Physics at the SCRIT Electron Scattering Facility

A large-acceptance detector system for electron scattering from polarized internal targets

The design and the performance of a non-magnetic detector setup for internal target physics at the NIKHEF electron-scattering facility is described. The detector setup, used in the first internal-target experiment at the AmPS ring, measures the spin dependence in the elastic and break-up reaction channels from tensor polarized deuterium. It has been established that the detector setup can operate adequately in an internal target environment at luminosities up to 10 32 e − atoms cm −2 s −1. Results and measured resolutions are presented.

A low-mass vacuum exit foil for high energy electrons and hadrons

The low-mass exit-foil system for the spectrometers in the electron-scattering facility at NIKHEF-K is described. It facilitates the achievement of high momentum resolution as well as the possibility to use the spectrometers for detection of not only protons but also deuterons, tritons, 3He and 4He. The system is constructed of very thin Kapton and Mylar foils reinforced with Kevlar material and features a differential pumping system.

Transverse electroexcitation of positive- and negative-parity states in 19F

Transverse electroexcitation of states in 19F at excitation energies below 4.4 MeV is described. Cross-section measurements were performed with the 500 MeV electron-scattering facility at NIK.-HEF-K at a scattering angle of 154° and in the momentum-transfer range q = 1.4–2.6 fm −1. Some additional low- q data were measured with the 180° electron-scattering facility. The form factors for the negative-parity states are compared with predictions from a 1 ħω shell-model calculation in the full 1p-2sld configuration space. For the positive-parity states a comparison is made with 0 ħω shell-model calculations in the full 2s1d configuration space and with 2 ħω shell-model calculations in a space made up of all shells up to the 1 f 7 2 orbit. The large differences observed between the form factors calculated in the 0 ħω and 2 ħω spaces are ascribed to effects of space truncation.

The 180° electron-scattering facility at Nikhef-K

An electron-scattering facility is describes that received low-energy electron beams with E 0 ≦ 140 MeV from the 500 MeV medium energy accelerator. It is equipped with a 180° scattering system with a relatively large solid angle (2.9 msr) and a broad momentum acceptance. Electrons scattered between 177° and 183° can be detected with a 19-channel overlapping-scintillator system placed in the focal plane of a magic-angle spectrometer. Various test results are shown to demonstrate the performance of the system.

The 500 MeV electron-scattering facility at NIKHEF-K

The 500 MeV electron-scattering facility, designed and built in conjunction with the 500 MeV, 2.5% duty factor electron linear accelerator (MEA), has been completed. It allows high-resolution (1 × 10 −4) single-arm (e,e′) experiments with a QDD spectrometer and single-arm hadron detection [( γ, π) and (γ,p) reactions] with a large solid angle (17 msr) QDQ spectrometer. With both specrometers coincidence experiments (e,e′ x) can be performed with a 225 keV missing energy resolution and a 1 ns timing resolution. A comprehensive description is given of the beam-handling system, spectrometers, detection system, data handling techniques and other instrumentation. Finally, test results obtained at energies ranging from 70 to 460 MeV are presented.

Discovery of a6−,T=1Resonance inMg24via High-Resolution Inelastic Electron Scattering

The unique high-resolution and high-energy features of the electron-scattering facility at the MIT-Bates Accelerator were used to locate a dominant narrow resonance at 15.045 \ifmmode\pm\else\textpm\fi{} 0.035 MeV in $^{24}\mathrm{Mg}$. A spin-parity assignment of ${6}^{\ensuremath{-}}$ and an isospin $T=1$ assignment were made. The $M6$ form factor was measured and compared to the prediction of a theoretical calculation which uses the open-shell random-phase approximation on a shell-model ground state for $^{24}\mathrm{Mg}$.