Biomedical subjects

X M Maréchal

Publications and source records attributed to X M Maréchal.

10 recordsLinked to original sources

PubMed1998

Performance of a helical undulator of the UVSOR.

A helical undulator was installed in the 0.75 GeV storage ring of the UVSOR facility of the Institute for Molecular Science. The undulator was designed to produce the fundamental of the circularly polarized undulator radiation in the energy range 2-43 eV, and the higher harmonics with elliptical polarization in the energy range up to 300 eV. Recently, the first spectrum from the undulator was observed. The performance of the undulator and the obtained spectrum are reported.

Journal Article↗

PubMed1998

In-vacuum figure-8 undulator for hard X-rays with both horizontal and vertical polarization.

A figure-8 undulator of the in-vacuum type has been adopted as an insertion device for BL24XU, the Hyogo Beamline at SPring-8, to provide hard X-rays with both horizontal and vertical polarization instead of a tandem undulator consisting of horizontal and vertical undulators. The undulator will be operated with the gap almost fixed at 11.6 mm to provide the fundamental radiation with horizontal polarization at 9.5 keV and the 1.5th harmonic with vertical polarization at 14 keV.

Journal Article↗

PubMed1998

An insertion device for the soft X-ray photochemistry beamline at SPring-8.

A figure-8 undulator is an insertion device (ID) proposed at SPring-8 to reduce the heat-load problems encountered with ordinary linear undulators. This device is useful when the K value is high in order to obtain low-energy photons as the fundamental of the undulator radiation. It has therefore been adopted as the ID for the soft X-ray photochemistry beamline (BL27SU) at SPring-8 because linearly polarized photons between 100 and 2000 eV are necessary for the experiments on this beamline. The figure-8 undulator for BL27SU is now under construction and, in the first phase of operation, is expected to cover the energy range down to 500 eV. In the second and third phases, the lowest energy may be reduced to 170 and 100 eV, respectively.

Journal Article↗

PubMed1998

Construction of a vertical undulator at SPring-8.

A new-type insertion device (ID) has been constructed for the structural-biology beamline (BL45XU) at SPring-8. The ID consists of two undulators which can provide vertical polarized radiation (vertical undulators). By changing the individual gap of each undulator independently, photons with two different energies can be obtained. Magnetic field measurements show that the maximum horizontal field is 0.49 T and the magnetic performance is as good as expected.

Journal Article↗

PubMed1998

SPring-8 in-vacuum undulator beam test at the ESRF.

Before the commissioning of SPring-8, the in-vacuum hybrid undulator developed at SPring-8 had been brought to the ESRF for the first beam test in the summer of 1996. The purpose of this test was to investigate the influence of the in-vacuum undulator on the beam and check its vacuum system. However, heating by the resistive wall impedance turned out to be a critical issue for the in-vacuum undulators.

Journal Article↗

PubMed1998

Development of an in-vacuum minipole undulator.

An in-vacuum minipole (short-period) insertion device has been developed in a collaboration between SPring-8 and the National Synchrotron Light Source (NSLS). The magnetic arrays were constructed by SPring-8 and were installed in a chamber with mechanical parts in the X-ray ring (E = 2.584 GeV) at the NSLS in May 1997. The device is made of permanent magnets with 30.5 periods and a period length of 11 mm. It is designed to produce fundamental radiation at 4.6 keV, and, with a modest value of deflection parameter (K = 0.7 at 3.3 mm gap), enables higher harmonics to be used for a variety of experiments.

Journal Article↗

PubMed1998

SPring-8 twin helical undulator.

There are several ways of producing circularly polarized light, such as using asymmetric devices, crossed undulators etc. The SPring-8 helical undulator introduces a simple way of producing both horizontal and vertical fields in one undulator. All the magnet arrays are arranged above and below the plane of the electron orbit, so there is no limitation of access from the sides of the undulator. For the SPring-8 BL25SU, two helical undulators will be installed in tandem, and the helicity of the polarization can be switched at up to 10 Hz using five kicker magnets.

Journal Article↗

PubMed1998

In-vacuum undulators of SPring-8.

Most of the SPring-8 insertion devices are in-vacuum undulators except for the soft X-ray devices and one elliptical wiggler. The standard-type SPring-8 in-vacuum undulator has a period of 32 mm and a minimum gap of 8 mm. The fundamental radiation energy ranges from 5.2 to 18.5 keV. Three standard in-vacuum undulators are already installed in the ring and are operating without any problems. The magnetic field correction, the vacuum system and the commissioning of the in-vacuum undulators are described in this paper.

Journal Article↗

PubMed1998

Development of an elliptical multipole wiggler at SPring-8.

An elliptical multipole wiggler (EMPW) based on a new concept has been installed on the SPring-8 storage ring. The EMPW, with a 120 mm period, has a critical energy of 50 keV at a gap of 20 mm. It will provide high-brilliance hard circularly polarized X-rays in the 100-300 keV range to the pilot beamline dedicated to materials science: the Compton scattering beamline. Field measurements, field integrals, the expected fluxes, polarization rates, power and power densities are presented for two operating gaps: 30 mm during commissioning, 20 mm later.

Journal Article↗

PubMed1998

Performance of a fixed-taper in-vacuum undulator at SPring-8.

With an in-vacuum undulator, the smallest gaps can be used to achieve high-brilliance radiation within a small spectral width around the harmonics of the fundamental. However, some experiments require a scan over a much wider range of energy within timescales which are impossible to reach via gap tuning. For standard undulators a flat spectrum is usually obtained by using a variable tapered gap. Unfortunately, the mechanical design of the in-vacuum undulator used at SPring-8 is hardly compatible with the extra degree of freedom necessary to adjust the taper mechanically. New magnetic designs are investigated to overcome this problem; their performances are compared with the performances of a fixed-taper in-vacuum undulator for a source of photons in the 5-15 keV range (energy of the fundamental) with an energy width of 1.5 keV.

Journal Article↗