Journal of Neutron Research - Volume 4, issue 1-4

Authors: Rausch, C.

Article Type: Research Article

Abstract: The readout of neutron scintillators via CCD cameras has proved to be an efficient and cost effective means of position sensitive neutron detection. Slow-scan CCDs work as integrating detectors, offering high count rate capability and high linearity, whereas intensified CCDs allow the analysis of single neutron events, thus providing good background rejection at lower count rates. This paper describes the workings of a slow-scan CCD camera for neutron detection and reports about properties of various types of scintillators, fiber optic devices, lenses and CCDs that are used for these detectors, and their influence on the detective quantum efficiency.

DOI: 10.1080/10238169608200071

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 87-95, 1996

Authors: Crawford, R.K.

Article Type: Research Article

Abstract: The principles involved in gas detectors for neutrons and the techniques for position encoding in such detectors are reviewed. This forms the basis for a discussion of the limitations on gas detector position resolution and maximum data rates, and of the aging effects in such detectors. Current capabilities and possible areas for improvement are noted.

DOI: 10.1080/10238169608200072

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 97-107, 1996

Authors: Ottonello, P. | Rottigni, G.A. | Zanella, G. | Zannoni, R.

Article Type: Research Article

Abstract: A review is presented about the use of scintillating glass optical fibers for neutron imaging. The fibers are assembled in bundles to form plates coupled to integrating image detectors (CCDs). The scintillating glass core of the single fibers, which are oriented in the direction of impinging neutrons, is sensitive to neutrons. Scintillating glasses containing lithium and doped with terbium or europium are the most convenient for detection of slow neutrons. Experimental results are reported.

DOI: 10.1080/10238169608200073

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 109-116, 1996

Authors: Knitel, M.J. | Dorenbos, P. | de Haas, J.T.M. | , C.W.E. | van Eijk,

Article Type: Research Article

Abstract: We report on the scintillation properties of a LiBaF3 crystal when irradiated with thermal neutrons or gamma rays. This scintillator exhibits cross luminescence and self-trapped-exciton luminescence. The former does not show up under thermal-neutron irradiation, whereas both give a response under gamma irradiation. This offers a unique opportunity for thermal-neutron - gamma discrimination. The effectiveness of the method is demonstrated.

DOI: 10.1080/10238169608200074

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 117-121, 1996

Authors: Hutchinson, D.P. | Miller, V.C. | Ramsey, J.A.

Article Type: Research Article

Abstract: A proposed design for an optically-based, one-dimension scintillation detector to replace the gas-filled position-sensitive proportional counter currently used for a wide-angle neutron detector (WAND) at the High-Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) is presented. The scintillator, consisting of a mixture of 6 LiF and ZnS(Ag) powders in an epoxy binder, is coupled to an array of wavelength shifting optical fibers which provide position resolution. The wide-angle neutron detector is designed to cover a 120 degree arc with a 75 cm radius of curvature. The final detector design provides for 600 optical fibers coupled to the …scintillator screen with an angular resolution of 0.2 degrees. Each individual pixel of the detector will be capable of operating at count rates exceeding 1 MHz. Results are presented from the measurement of neutron conversion efficiencies for several screen compositions, gamma-ray sensitivity and spatial resolution of a 16 element one-dimensional array prototype. Show more

DOI: 10.1080/10238169608200075

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 123-127, 1996

Authors: Rhodes, N.J. | Johnson, M.W. | , C.W.E. | van Eijk,

Article Type: Research Article

Abstract: This paper describes the scintillators in common use for the detection of thermal neutrons and the advantages of using scintillator technology in the design of neutron detectors. Characteristics obtained in recent detectors incorporating these scintillators are given together with proposals for new scintillator detectors under development at ISIS. Desired characteristics of new scintillators for use in neutron detectors at both ISIS and new accelerator sources are defined.

DOI: 10.1080/10238169608200076

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 129-133, 1996

Authors: Müller, K.D. | Reinartz, R. | Engels, R. | Reinhart, P. | Schelten, J. | Schäfer, W. | Jansen, E. | Will, G.

Article Type: Research Article

Abstract: The paper presents the spectrum of solid state neutron scintillation detectors, which have been developed and manufactured at Jiilich with respect to use at neutron scattering instruments at steady state reactors and pulsed spallation sources. Design and physical characteristics of three types of linear and three types of area detectors are described. The detectors are designed for operation as standalone PC-based systems with integrated timing interface based on programmable logic cell arrays. The data acquisiton system within the EISA-PC is suitable for applications requiring huge amounts of memory, e.g. in position-sensitive time-of-flight experiments.

DOI: 10.1080/10238169608200077

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 135-140, 1996

Authors: Bruckner, G. | Rauch, H.

Article Type: Research Article

Abstract: Si-strip detectors show qualities which are desirable in many neutron experiments, like excellent position– and time resolution and a low sensitivity to background radiation. To demonstrate the feasibility of this detector type for the detection of thermal neutrons, we tested a prototype of a one dimensional position sensitive neutron detector based on a Si-strip detector with a Gd-foil converter. A complete system consisting of the detector with VLSI electronics and an on-line data acquisition system has been constructed and tested. We present the first results of the measured position resolution and detector efficiency for neutrons with 1.1 Å wavelength.

DOI: 10.1080/10238169608200078

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 141-147, 1996

Authors: Rauch, H.

Article Type: Research Article

Abstract: Perfect crystal neutron interferometry has provided the basis for the realization of many basic experiments for testing quantum mechanics with massive particles. The following quantum effects have been verified: 4π-symmetry of spinors, spin-superposition, gravity-induced quantum interference effects, the Aharonov-Casher effect, the magnetic Josephson effects, the scalar Aharonov-Bohm effect etc. More recently, steps towards neutron quantum optics have been undertaken. Measurements have dealt with the coherence properties of the neutron beam, the photon exchange between the neutron and various electromagnetic fields, the particle number-phase uncertainty, squeezing phenomena, and the Wigner-functional behavior of a neutron system. These achievements opened the field of …direct Fourier spectroscopy which brings a direct access to the space and time dependent correlation functions which describe condensed matter. Various perspectives for further experiments in the field of fundamental and condensed matter physics are discussed. Show more

DOI: 10.1080/10238169608200079

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 149-156, 1996

Authors: Ebisawa, T. | Funahashi, H. | Tasaki, S. | Otake, Y. | Kawai, T. | Hino, M. | Achiwa, N. | Akiyoshi, T.

Article Type: Research Article

Abstract: Cold neutron interferometry using multilayer mirrors is discussed. The interferometry includes two kinds of multilayer interferometers, which are analogous optically to the Mach-Zehnder and the Jamin interferometer in classical optics. The Mach-Zehnder multilayer interferometer has been installed at JRR-3M reactor of JAERI. We describe the conditions required for the Mach-Zehnder multilayer interferometer and the characteristics of the interferometer. The Jamin multilayer interferometer, called a phase echo interferometer, shows a phase echo effect analogous functionally to the spin echo principle. We describe briefly the first successful performance tests. We propose a phase echo spin interferometer using multilayer spin splitters, based on …the phase echo principle and the coherent superposition of the spin eigenstates. Show more

DOI: 10.1080/10238169608200080

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 157-166, 1996

Authors: Hewat, A.W.

Article Type: Research Article

Abstract: Crystals, counters and computers are the most important new tools for powder diffraction. New crystal monochromators allow a wide band of wavelengths to be focussed to give higher intensity. New position sensitive detectors cover a larger angular range, increasing efficiency and the definition of the powder profile. Finally, new computers refine and display the data in real time, converting measurements into real experiments. These new technical developments will allow neutron powder diffraction on reactors to remain unique tools in chemical crystallography, despite advances made with pulsed sources and synchrotrons. In this paper we describe a new monochromator and filter for …D2B, new detectors for DlA and D20 and new computers and software for all diffractometers. Show more

DOI: 10.1080/10238169608200081

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 167-173, 1996

Authors: Kahn, R. | Menelle, A.

Article Type: Research Article

Abstract: Industrial manufacture of surfaces coated with supermirror of enhanced critical angle and high reflectivity allows new developments in the use of neutron guide. We report some new results on Ni/Ti multilayer: influence of adding Carbon in the Ni layers and time evolution with irradiation of the reflecting properties. Also we present briefly the flux and wavelength distribution available at the end position of a multilayer coated bender and of a classical guide where only the curved section is made of supermirror-type elements.

DOI: 10.1080/10238169608200082

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 175-181, 1996

Authors: Lamoreaux, Steve K.

Article Type: Research Article

Abstract: Recent theoretical and experimental progress on the development of new techniques for measuring the neutron electric dipole moment and neutron lifetime, and for producing ultracold neutrons in general, is reviewed, with emphasis on the electric dipole moment work. The basic idea is to produce and store ultracold neutrons in a superfluid 4 He bath which has been doped with a low concentration of polarized 3 He which serves as an ultracold neutron polarizer, analyzer, and magnetometer.

DOI: 10.1080/10238169608200083

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 183-190, 1996

Authors: Bowles, Thomas J.

Article Type: Research Article

Abstract: Ultra Cold Neutrons (UCN) can be produced at spallation sources using a variety of techniques. To date the technique used has been to Bragg scatter and Doppler shift cold neutrons into UCN from a moving crystal. This is particularly applicable to short-pulse spallation sources and is the method planned for a UCN source that is under construction at LANSCE. However, large gains should be possible using cryogenic UCN sources. Spallation sources are particularly well suited for such sources given the lower heat loads and simpler engineering requirements than are possible at a reactor. The most attractive cryogenic source appears to …be a frozen deuterium source and research is under way at Gatchina to demonstrate technical feasibility. If successful, a source of this type could be implemented at future spallation sources with a UCN density that may be two orders of magnitude higher than that presently available at reactors. Show more

DOI: 10.1080/10238169608200084

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 191-196, 1996

Authors: Masuda, Y.

Article Type: Research Article

Abstract: P-violating neutron-spin rotation was firstly observed in a p-wave neutron-nucleus resonance. A lanthanum target was placed in a superconducting box. The incident neutron spin was set at transverse direction to the neutron beam in the horizontal plane. The neutron spin rotates around its momentum axis in the presence of P-violating interaction. The neutron spin passes through a Meissner sheet without any change in its direction. The rotation angle was converted to a projection angle on a vertical magnetic field in the downstream, which was analyzed by a polarized 3 He neutron polarimeter. The experimental result of the P-violating rotation is …consistent with the theory of s- and p-wave parity mixing in the compound nucleus state. For the T-violation experiment, measurement of T-odd triple correlation between the neutron spin, the neutron momentum and the nuclear spin, a new method is proposed, which greatly reduces systematic errors. The experiment can be compared with the neutron electric dipole moment. Target-nucleus polarization was developed for the T-violation experiment by using a dynamic nuclear polarization. A large lanthanum nuclear polarization was obtained. Show more

DOI: 10.1080/10238169608200085

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 197-208, 1996

Authors: Knudson, J.N. | Bowman, J.D. | Crawford, B.E. | Delheij, P.P.J. | Frankle, C.M. | Gould, C.R. | Haase, D.G. | Iinuma, M. | Lowie, L.Y. | Masaike, A. | Masuda, Y. | Matsuda, Y. | Mitchell, G.E. | Penttila, S.I. | Postma, H. | Roberson, N.R. | Seestrom, S.J. | Sharapov, E.I. | Shimizu, H.M. | Stephenson, S.L. | Yen, Y.F. | Yuan, V.W. | Yoo, S.H.

Article Type: Research Article

Abstract: We describe an apparatus for studies of parity violation in neuwn-nucleus scattering. This experiment requires longitudinally polarized neutrons from the Los Alamos Neutron Scattering Center over the energy range from 1 to l000 eV, the ability to reverse the neutron spin without otherwise affecting the apparatus, the ability to detect neutrons at rates up to 500 MHz and an appropriate data acquisition system. We will discuss the neutron polarizer, fast neutron spin reverser, detector for transmitted neutrons and high rate data acquisition system.

DOI: 10.1080/10238169608200086

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 209-213, 1996

Authors: Otake, Yoshié | Zeyen, Claude M.E. | Forte, Mario

Article Type: Research Article

Abstract: Antisymmetric interactions with respect to spin direction give rise to spin rotations in certain perfect crystals. A new perfect crystal technique, termed Dual-Polarised-Beam technique (DPB), can be used to boost the sensitivity of the spin rotation measurements by several orders of magnitude. The typical Zeeman splitting is shown and a future experiment of neutron EDM detection with DPB using new crystals is also discussed.

DOI: 10.1080/10238169608200087

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 215-219, 1996

Authors: Stuhrmann, Heinrich B.

Article Type: Research Article

Abstract: Polarized neutron scattering is a probe of nuclear spin densities. It finds an important application in nuclear spin contrast variation. As an example the results from studies on ribosome bound tRNAs are presented. Selective nuclear spin polarization can be controlled by the rf bandwidth. The creation of spin label dependent polarization domains is at hand.

DOI: 10.1080/10238169608200088

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 221-226, 1996

Authors: Schärpf, O. | Anderson, I.S.

Article Type: Research Article

Abstract: To show the rich scale of possibilities of the classical polarization analysis we first give a short overview of measuring techniques. Then we compare some known instruments and give some details for the use of classical polarization analysis in a multidetector instrument. Some examples of measurements already performed are discussed such as partial structure factors with separation of elastic coherent and incoherent scattering, diffraction patterns with elastic antiferromagnetic peaks and finally some examples of quasielastic and inelastic measurements with polarization analysis for separation of coherent, incoherent and magnetic scattering.

DOI: 10.1080/10238169608200089

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 227-240, 1996

Authors: Zeyen, Claude M.E. | Kakurai, Kazuhisa

Article Type: Research Article

Abstract: Because of the stringent requirements on the magnetic precession fields this technique has taken a long implementation time. The solution of the homogeneity and of the stray-field problem is the Optimal Field Shape (OFS) which allows the use of wide and divergent neutron beams. On the ISSP thermal three-axis spectrometer equipped with OFS coils relative energy resolutions of l0−5 have now been obtained. At the ILL the implementation of super conducting OFS coils is expected to yield 10−6 . The quality of the spin-echo polarisation and the spin echo phase are independent of the scattering angle. A further possibility …of TASSE (Three Axis Spectrometer with Spin Echo) which has been developed and is to be tested, is complete phonon focusing, that is matching of both slope and curvature of the constant spin echo phase surface to those of the dispersion surface of the excitation, the lifetime of which is to be determined. Show more

DOI: 10.1080/10238169608200090

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 241-250, 1996

Authors: Fermon, C. | Miramond, C. | Ott, F. | Saux, G.

Article Type: Research Article

Abstract: We summarise the theory of polarised neutron reflectivity and describe the PADA reflectometer at the Orphée reactor at Saclay France. We then discuss some experimental difficulties and highlight how this apparatus can be applied to the study of thin magnetic films. Finally, we give an example of a recent experiment on Au/Co/Au trilayers.

DOI: 10.1080/10238169608200091

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 251-260, 1996

Authors: Köppe, Maro | Hank, Peter | Wuttke, Joachim | Petry, Winfried | Gähler, Roland | Kahn, Rémi

Article Type: Research Article

Abstract: We present the neutron resonance spinecho-spectrometer (NRSE) that was recently installed at the LLB-Saclay. Brief quantum mechanical descriptions of the spectrometer principle and of the main components, the RF-flippers, are given. We also discuss the technological details of these flippers. The spinecho-curves clearly demonstrate the good performance of the instrument. A first quasielastic neutron scattering measurement on the structural relaxations of the glass former deuterated glycerol shows the high flexibility and reliability of the new spectrometer, but also indicates the need to increase the primary intensity, planned in near future.

DOI: 10.1080/10238169608200092

Citation: Journal of Neutron Research, vol. 4, no. 1-4, pp. 261-273, 1996