Ornl Neutron Sciences Update

Vol. 12 n. 2 July 2007 • NOTIZIARIO NEUTRONI E LUCE DI SINCROTRONE

MUON & NEUTRON &SYNCHROTRON RADIATION NEWS

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(Fig. 1). The development of onlineoptical pumping of 3He gas to main-tain time-independent neutronicperformance is underway for a fewinstruments.The key technical challenges in ap-plying 3He spin filters to neutronscattering are 1) producing a largevolume of highly polarized 3He gasand 2) minimizing the 3He polariza-tion decay.We have constructed two SEOP sys-tems capable of producing 75 % po-larized 3He gas at pressures of (1 to2) x 105 Pa in cells having volumes

approaching 1 L. To reduce polariza-tion relaxation arising from field gra-dients inside magnetically shieldedsolenoids, we have optimized thefield homogeneity by modeling andmapping the field, and most useful-ly, by measuring the polarization re-laxation of the sealed low-pressureMEOP cells.We have built a few compact mag-netically shielded solenoids thatyield field-gradient induced relax-ation times up to 3000 h for a 3Hepressure of 105 Pa over a cell volumeof 1 L.

References1. A. Abragam, Principles of Nuclear Magnetism,

Oxford University Press, Oxford, England(1961).

2. W.C. Chen et al., Rev. Sci. Instrum. 75, 3256(2004).

3. T.R. Gentile et al., J. Appl. Cryst. 33, 771(2000).

4. W.C. Chen et al., Physica B in press.

W.C. Chen, J.A. Borchers,R. Erwin, T.R. Gentile,

J.W. LynnNational Institute

of Standards and Technology,Gaithersburg, Maryland, USA

News from SNSORNL Neutron Sciences UpdateBoth Oak Ridge National Laboratoryneutron scattering facilities complet-ed safety reviews in April 2007.These successes enable the High FluxIsotope Reactor (HFIR) and the Spal-lation Neutron Source (SNS) to con-tinue preparations for users to per-form neutron scattering experiments.A recently developed web-basedproposal submission process enablesboth facilities to coordinate beamtime on the neutron scattering in-

struments through a combined userprogram. The Integrated ProposalTracking System is undergoing betatesting. It will track proposalsthroughout the experimentalprocess, including proposal submis-sion, safety and science reviews, andbeam time scheduling. The HighFlux Isotope Reactor passed a formalreview assessing readiness for restartof operations. Neutron production isexpected to begin again in early May

2007. It is anticipated that the initialcycles will be devoted to testing ofinstruments and operational para-meters, with general users arrivinglater this summer. Four HFIR instru-ments will be initially available fol-lowing restart of the reactor: threetriple-axis spectrometers and theresidual stress diffractometer. Futurecapabilities at world-class levels willbe enabled by a new cold source fortwo small-angle neutron scattering

Figure 1. A 24-ton portion of the 65m3 ARCSscattering tank is lifted into position.Photo credit: Mark Loguillo/ORNL.

Figure 2. The POWGEN3 powder diffractometer team has completed installation of neutron guide.Photo credit: Luke Heroux/ORNL.

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NOTIZIARIO NEUTRONI E LUCE DI SINCROTRONE • Vol. 12 n. 2 July 2007


beam lines; these will be directed tothe biomaterials, pharmaceutical,and polymer communities. In com-ments referring to the re-start ofHFIR operations, ORNL groupleader Greg Smith said “Neutronscatterers are anxious to start doingexperiments using the facilities nowavailable at HFIR. In particular, thecold neutrons will give us new capa-bilities almost immediately to studycomplex molecules and biologicalsamples using the new SANS instru-ments in the guide hall. These instru-ments, combined with our state-of-the-art spectrometers already in thebeam room, will certainly usher in anew era of scientific productivity forORNL researchers and users fromaround the world”. The most recentSNS operation cycle was completedApril 15, 2007. A review was heldApril 2007 to assess readiness for ac-celerator operations at proton beampower above our present 100 kW ap-

proved limit up to the design capa-bility of 2 MW. Power of the acceler-ator will be increased beyond 100kWas the predictability and reliability ofneutron production also increases. Inthe most recent SNS operations cy-cle, proton beam power routinely de-livered to the target achieved thegoal of approximately 60 kW at anoperating frequency of 15 Hz. Theaccelerator also operated for fourhours at 90 kW. In another test of theaccelerator system, the operating fre-quency was increased to 30 Hz forseveral hours of neutron productionat 30 kW; this is in preparation forincreasing the power during the nextoperations cycle. A new world ener-gy record for proton beam accelera-tion in a linear accelerator was set onFebruary 19, 2007. SNS acceleratedthe proton beam to 1.01 GeV, break-ing the previous record of 0.95 GeV,which SNS achieved in December2005, and reaches the intended de-

sign energy of 1.0 GeV. The firstthree SNS instruments continue theircommissioning with the goal of wel-coming general users in October2007: BASIS – Backscattering Spec-trometer, and the Magnetism andLiquids Reflectometers.This involves testing major compo-nents such as the data acquisitionsystem, neutron choppers, incidentbeam monitor, and neutron detec-tors. Test measurements of varioussamples have been performed. Test-ing of this equipment including se-lected sample environments and po-larizers will continue during the nextoperations cycle. Advances continuein the construction of other instru-ments at SNS with an extremelybusy period of commissioning anduser activity beginning in fall 2007(see accompanying table).The POWGEN3 powder diffrac-tometer finished guide installationand 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

Vol. 12 n. 2 July 2007 • NOTIZIARIO NEUTRONI E LUCE DI SINCROTRONE


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In late March, 55 state and federaljudges came to Lawrence BerkeleyNational Laboratory for a week-longconference designed to give thejudges an orientation to the emerg-ing fields of nanotechnology, syn-thetic biology, and environmentalbiotechnology, and enhance theirability to preside over complex cases

involving novel scientific evidence.They toured the Advanced LightSource, focusing on its protein andcellular imaging capabilities.They also toured a nanotechnologyresearch center, met with BerkeleyLab Director Chu and several otherLab scientists, isolated DNA frag-ments and examined spectroscopyimages, and dissected imaginarycases involving nanoparticles, ra-dionuclide releases, and bioremedia-tion. “They came to Berkeley Lab be-cause we are known as the center forscience, and they need to know howscience works”, says Terry Hazen, amicrobial ecologist in the Earth Sci-ences Division who has helpedjudges bone up on the fundamentalsof science for the past eight years. Hazen organized the March 25 toMarch 30 conference under the aus-pices of the Advanced Science &

Technology Adjudication ResourceCenter (ASTAR), a non-profit corpo-ration that seeks to improve the ca-pacities of the nation’s courts in re-solving highly technical cases.Judges who attended the conferencewere certified by ASTAR and willprovide case-related leadership laterthis year at the group’s national con-ferences.ASTAR’s mission over the next twoyears is to provide an orientation onthe fundamentals of emerging scien-tific disciplines to every court juris-diction in the U.S.

D. KrotzCommunications Department

Lawrence Berkeley National Labphone: (510) 486-4019

fax: (510) [email protected]

Judges come to Lawrence Berkeley National Lab to learnabout Science

Judges get an orientation to emerging scientificfields from Lab microbial ecologist Terry Hazen.

guide sections. Large sample vesselsfor ARCS - Wide Angular RangeChopper Spectrometer [volume of 65m3] and SEQUOIA – Fine ResolutionFermi Chopper Spectrometer [vol-ume of 250 m3] have been receivedand installed.Construction of the external instru-ment buildings for the CNCS – ColdNeutron Chopper Spectrometer and

VULCAN – Engineering Diffrac-tometer is scheduled for completionin summer 2007.

ORNL User Meeting October 8-12,2007Four ORNL user facilities – SNS,HFIR, the Center for Nanophase Ma-terials Sciences, and the Shared Re-search Equipment user facilities –are coordinating a program for acombined User Week, October 8-12,2007, to be held at ORNL. The firstgoal of this meeting is to increase in-

terest and awareness of the impor-tant scientific research challengesthat are being addressed at these

Oak Ridge facilities. Second, wewish to receive feedback on neededadvances in areas such as develop-ing pump-probe techniques to studynon-equilibrium phenomena at mi-crosecond timescales, combiningsample environment stages (perhapshigh magnetic fields, high pressure,and low temperature simultaneous-ly), and combining characterizationtechniques (x-ray and neutron) onthe same instrument. Third, there isan opportunity to acquaint newusers with capabilities of some of themajor techniques used at SNS andHFIR through small workshops.More information on this combineduser meeting, including registration,agenda, and lodging, can found athttp://neutrons.ornl.gov or by emailto [email protected].

A.E. EkkebusNeutron Scattering Science Division

Oak Ridge National Laboratory

Figure 3. This UV image is usedto assess optical alignment ofneutron guide sections of theVULCAN engineering diffrac-tometer. Note the continuoussmooth lines from the cornerswith no breaks or jumps whereglass sections meet.Image credit: Marc Shoemak-er/ORNL.

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Ornl Neutron Sciences Update