Ornl Neutron Sciences Update


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Ornl Neutron Sciences Update

  1. 1. MUON & NEUTRON & SYNCHROTRON RADIATION NEWS (Fig. 1). The development of online approaching 1 L. To reduce polariza- References optical pumping of 3He gas to main- 1. A. Abragam, Principles of Nuclear Magnetism, tion relaxation arising from field gra- Oxford University Press, Oxford, England tain time-independent neutronic dients inside magnetically shielded (1961). performance is underway for a few solenoids, we have optimized the 2. W.C. Chen et al., Rev. Sci. Instrum. 75, 3256 instruments. field homogeneity by modeling and (2004). The key technical challenges in ap- mapping the field, and most useful- 3. T.R. Gentile et al., J. Appl. Cryst. 33, 771 plying 3He spin filters to neutron ly, by measuring the polarization re- (2000). scattering are 1) producing a large laxation of the sealed low-pressure 4. W.C. Chen et al., Physica B in press. volume of highly polarized 3He gas MEOP cells. W.C. Chen, J.A. Borchers, and 2) minimizing the 3He polariza- We have built a few compact mag- R. Erwin, T.R. Gentile, tion decay. netically shielded solenoids that J.W. Lynn We have constructed two SEOP sys- yield field-gradient induced relax- ation times up to 3000 h for a 3He National Institute tems capable of producing 75 % po- of Standards and Technology, larized 3He gas at pressures of (1 to pressure of 105 Pa over a cell volume Gaithersburg, Maryland, USA 2) x 105 Pa in cells having volumes of 1 L. News from SNS ORNL Neutron Sciences Update Both Oak Ridge National Laboratory struments through a combined user 2007. It is anticipated that the initial neutron scattering facilities complet- program. The Integrated Proposal cycles will be devoted to testing of ed safety reviews in April 2007. Tracking System is undergoing beta instruments and operational para- These successes enable the High Flux testing. It will track proposals meters, with general users arriving Isotope Reactor (HFIR) and the Spal- throughout the experimental later this summer. Four HFIR instru- lation Neutron Source (SNS) to con- process, including proposal submis- ments will be initially available fol- tinue preparations for users to per- sion, safety and science reviews, and lowing restart of the reactor: three form neutron scattering experiments. beam time scheduling. The High triple-axis spectrometers and the A recently developed web-based Flux Isotope Reactor passed a formal residual stress diffractometer. Future proposal submission process enables review assessing readiness for restart capabilities at world-class levels will both facilities to coordinate beam of operations. Neutron production is be enabled by a new cold source for time on the neutron scattering in- expected to begin again in early May two small-angle neutron scattering Figure 1. A 24-ton portion of the 65m3 ARCS Figure 2. The POWGEN3 powder diffractometer team has completed installation of neutron guide. scattering tank is lifted into position. Photo credit: Luke Heroux/ORNL. Photo credit: Mark Loguillo/ORNL. Vol. 12 n. 2 July 2007 • NOTIZIARIO NEUTRONI E LUCE DI SINCROTRONE 33
  2. 2. MUON & NEUTRON & SYNCHROTRON RADIATION NEWS beam lines; these will be directed to proved limit up to the design capa- sign energy of 1.0 GeV. The first the biomaterials, pharmaceutical, bility of 2 MW. Power of the acceler- three SNS instruments continue their and polymer communities. In com- ator will be increased beyond 100kW commissioning with the goal of wel- ments referring to the re-start of as the predictability and reliability of coming general users in October HFIR operations, ORNL group neutron production also increases. In 2007: BASIS – Backscattering Spec- leader Greg Smith said “Neutron the most recent SNS operations cy- trometer, and the Magnetism and scatterers are anxious to start doing cle, proton beam power routinely de- Liquids Reflectometers. experiments using the facilities now livered to the target achieved the This involves testing major compo- available at HFIR. In particular, the goal of approximately 60 kW at an nents such as the data acquisition cold neutrons will give us new capa- operating frequency of 15 Hz. The system, neutron choppers, incident bilities almost immediately to study accelerator also operated for four beam monitor, and neutron detec- complex molecules and biological hours at 90 kW. In another test of the tors. Test measurements of various samples using the new SANS instru- accelerator system, the operating fre- samples have been performed. Test- ments in the guide hall. These instru- quency was increased to 30 Hz for ing of this equipment including se- ments, combined with our state-of- several hours of neutron production lected sample environments and po- the-art spectrometers already in the at 30 kW; this is in preparation for larizers will continue during the next beam room, will certainly usher in a increasing the power during the next operations cycle. Advances continue new era of scientific productivity for operations cycle. A new world ener- in the construction of other instru- ORNL researchers and users from gy record for proton beam accelera- ments at SNS with an extremely around the world”. The most recent tion in a linear accelerator was set on busy period of commissioning and SNS operation cycle was completed February 19, 2007. SNS accelerated user activity beginning in fall 2007 April 15, 2007. A review was held the proton beam to 1.01 GeV, break- (see accompanying table). April 2007 to assess readiness for ac- ing the previous record of 0.95 GeV, The POWGEN3 powder diffrac- celerator operations at proton beam which SNS achieved in December tometer finished guide installation power above our present 100 kW ap- 2005, and reaches the intended de- and is installing shielding over the Schedule of ORNL Instruments through 2008 High Flux Isotope Reactor Spallation Neutron Source Scheduled for General User Program in 2007 HB-1, Polarized Triple-Axis Spectrometer BL 2 , BASIS - Backscattering Spectrometer HB-1A, Ames Lab Triple-Axis Spectrometer BL-4a, Magnetism Reflectometer HB-3, Triple-Axis Spectrometer BL-4b, Liquids Reflectometer HB-2B, Residual Stress Diffractometer Commissioning Scheduled for 2007, General Users in 2008 CG-2, 40m SANS BL-18, ARCS - Wide Angular Range Chopper Spectrometer CG-3, 35m BIOSANS Commissioning Scheduled for 2008, General Users in 2009 BL-3, High Pressure Diffractometer BL-5, CNCS – Cold Neutron Chopper Spectrometer BL-6, EQ-SANS – Extended Q-Range Small Angle Neutron Diffractometer BL-7, VULCAN – Engineering Diffractometer BL-11a, POWGEN3, Powder Diffractometer BL-13, Fundamental Physics Beam Line BL-17, SEQUOIA – Fine Resolution Fermi Chopper Spectrometer NOTIZIARIO NEUTRONI E LUCE DI SINCROTRONE • Vol. 12 n. 2 July 2007 34
  3. 3. MUON & NEUTRON & SYNCHROTRON RADIATION NEWS guide sections. Large sample vessels ORNL User Meeting October 8-12, Oak Ridge facilities. Second, we for ARCS - Wide Angular Range 2007 wish to receive feedback on needed Four ORNL user facilities – SNS, Chopper Spectrometer [volume of 65 advances in areas such as develop- m3] and SEQUOIA – Fine Resolution HFIR, the Center for Nanophase Ma- ing pump-probe techniques to study terials Sciences, and the Shared Re- Fermi Chopper Spectrometer [vol- non-equilibrium phenomena at mi- ume of 250 m3] have been received search Equipment user facilities – crosecond timescales, combining are coordinating a program for a and installed. sample environment stages (perhaps combined User Week, October 8-12, Construction of the external instru- high magnetic fields, high pressure, 2007, to be held at ORNL. The first ment buildings for the CNCS – Cold and low temperature simultaneous- goal of this meeting is to increase in- Neutron Chopper Spectrometer and ly), and combining characterization techniques (x-ray and neutron) on the same instrument. Third, there is Figure 3. This UV image is used an opportunity to acquaint new to assess optical alignment of users with capabilities of some of the neutron guide sections of the VULCAN engineering diffrac- major techniques used at SNS and tometer. Note the continuous HFIR through small workshops. smooth lines from the corners More information on this combined with no breaks or jumps where user meeting, including registration, glass sections meet. Image credit: Marc Shoemak- agenda, and lodging, can found at er/ORNL. http://neutrons.ornl.gov or by email to neutronusers@ornl.gov. A.E. Ekkebus terest and awareness of the impor- VULCAN – Engineering Diffrac- Neutron Scattering Science Division tant scientific research challenges tometer is scheduled for completion Oak Ridge National Laboratory that are being addressed at these in summer 2007. Judges come to Lawrence Berkeley National Lab to learn about Science In late March, 55 state and federal involving novel scientific evidence. Technology Adjudication Resource judges came to Lawrence Berkeley They toured the Advanced Light Center (ASTAR), a non-profit corpo- National Laboratory for a week-long Source, focusing on its protein and ration that seeks to improve the ca- conference designed to give the cellular imaging capabilities. pacities of the nation’s courts in re- judges an orientation to the emerg- They also toured a nanotechnology solving highly technical cases. ing fields of nanotechnology, syn- research center, met with Berkeley Judges who attended the conference thetic biology, and environmental Lab Director Chu and several other were certified by ASTAR and will biotechnology, and enhance their Lab scientists, isolated DNA frag- provide case-related leadership later ability to preside over complex cases ments and examined spectroscopy this year at the group’s national con- images, and dissected imaginary ferences. cases involving nanoparticles, ra- ASTAR’s mission over the next two dionuclide releases, and bioremedia- years is to provide an orientation on tion. “They came to Berkeley Lab be- the fundamentals of emerging scien- cause we are known as the center for tific disciplines to every court juris- science, and they need to know how diction in the U.S. science works”, says Terry Hazen, a microbial ecologist in the Earth Sci- D. Krotz ences Division who has helped Communications Department judges bone up on the fundamentals Lawrence Berkeley National Lab of science for the past eight years. phone: (510) 486-4019 Hazen organized the March 25 to fax: (510) 486-6641 March 30 conference under the aus- DAKrotz@lbl.gov Judges get an orientation to emerging scientific pices of the Advanced Science & fields from Lab microbial ecologist Terry Hazen. Vol. 12 n. 2 July 2007 • NOTIZIARIO NEUTRONI E LUCE DI SINCROTRONE 35