Robert Haight Los Alamos National Laboratory IAEA Technical Meeting on IFMIF FZK Karlsruhe October 4-6, 2005 LANSCE Nuclear Data Measurement Capabilities Ref: LA-UR

Outline LANSCE Capabilities Source characteristics Instruments People Missions (funding sources for LANSCE) Improvements planned

Nuclear physics experiments at LANSCE use neutrons at four locations: Line B, Lujan Center, Target 2 and Target 4. 90L 15R 30R 60R 90R Target 2 120L Weapons Neutron Research Facility 0.1 MeV < En < 600 MeV Line B NRAD, Ultra-Cold Neutrons Proton Radiography Area A (future MTS) ER-1 Target ER A/B H+ Source H- Source Isotope Production Facility Drift Tube Linear Accelerator Line D Side-Coupled Linear Accelerator PSR 15L 30L LSDS GEANIE FIGARO N,Z DANCE Proton Fission Lujan Center En < 500 keV

WNR -- Target Specifications Target-2 (Blue Room) Up to ~ 1 µA proton beam Proton induced reactions 6 flight paths Proton irradiations Lead slowing-down spectrometer (LSDS) Target-4 4 µA proton beam for high-energy neutron spallation source. Typical operation is 35,000 pulses/sec with 1.8 µsec spacing. 6 neutron flight paths Neutron induced reactions Energy spectrum depends on flight-path angle Determine energy of neutron by time-of-flight Neutron irradiations Proton beam

Lujan Center -- Moderated spallation source DANCE 800 MeV protons + tungsten -> fast neutrons (0.1 to 800 MeV) … then fast neutrons + H 2 O - > slower neutrons (subthermal to 1 MeV)

LANSCE neutron spectra cover energies from cold to several hundred MeV Moderated source (Lujan) Unmoderated source (WNR)

eV ultracold cold thermal epithermal fast Lujan (3) Area B(1) WNR (6) Target 2 (1 to 6) Neutrons at LANSCE span 16 orders of magnitude in energy LSDS Area & (number of flight paths)

Comparison of Lujan and WNR with ORELA Neutrons on sample From: Michaudon and Wender (1990)

Comparison with e.g. ORELA shows complementarity

Resolution comparisons for epithermal neutrons From Koehler: NIM A460, 352 (2001)

LANSCE Nuclear Physics Instruments Fast neutrons (En > 0.1 MeV) GEANIE – gamma-ray detector array of 26 HPGe detectors FIGARO – neutron detector array Frisch-grid fission ion chamber to measure cross sections, fission product yields, total energy released (n,z) instrument – silicon + CsI(Tl) for H and He measurements Total cross sections – (presently not active) Epithermal DANCE – 4-pi calorimeter for neutron capture- 160 BaF 2 detectors Frisch-grid fission ion chamber LSDS: fission chambers to measure fission cross sections on ultra-small samples

GEANIE (n,x  ) FIGARO (n,xn+  ) N,Z (n,charged particle) DANCE (n,  ) Fission Nuclear data measurements at LANSCE are made with several instruments LSDS Double Frisch-gridded fission chamber; also standard fission ion chamber Total cross sections

Most measurements use the time-of-flight technique pulsed 800 MeV proton beam tungsten target collimation shutter gamma rays faster neutrons slower neutrons 15 meters neutrons E n ~ v 2 ~ 1/t 2 (nonrelativistic) Time of flight over the flight path identifies the energy of the neutron that induces the reaction Reaction and detector area WNR Important characteristics: Neutron flux at sample Flux spectrum Time resolution Repetition rate “Gamma” flash Available flight paths Backgrounds

WNR neutron total cross sections were measured with ~ 1% absolute uncertainty in the 5 – 560 MeV range From: Finlay et al. (1993) and Abfalterer et al. (2001)

GEANIE: New data significantly improve the 193 Ir(n,n’) 193m Ir cross section database GEANIE LLNL/LANL

FIGARO: Measurements quantify how the fission neutron spectrum varies with incident neutron energy Agreement with Los Alamos Model is good below 20 MeV 238 U(n,f) average neutron energy Los Alamos Model FIGARO (n,f+xn ) From: Ethvignot et al., Phys. Lett. B575, 221 (2003). * Fission chamber

FIGARO: Neutron emission spectra are measured by triggering on gamma rays FIGARO (n,xn+  ) BaF 2 HPGe * From: Rochman et al. (2004)

(n,z) ( = hydrogen and helium production): LANSCE data differentiate among different evaluations From: Haight, ANS meeting (2004)

DANCE: 237 Np(n,  ) data are part of our AFCI program on actinides – sample is 0.44 mg Target: 0.44 mg 237 Np in 6.4 mm diameter (1.4 mg/cm 2 ) Technological development: 334 channels of waveform digitizers – process in < 50 ms  ~ 1GB/sec

The Lead Slowing-Down Spectrometer is driven by 800 MeV protons from the PSR Neutron trajectories following the interaction of 1 proton with the tungsten target in the lead cube

LSDS: We can now measure fission cross sections for samples smaller than 10 ng Ran 1  A of PSR beam to LSDS – radiation levels < 2 mR/hr outside of Blue Room Ran PSR at 30 Hz successfully Measured neutron-induced fission cross section of 239 Pu with a sample of 9.87 ng. Results agree with broadened ENDF/B-VI. Measured (n,  ) cross section with small 6 Li sample DAQ works well in present configuration. Digital filtering under development.  New shielding in BR hall  First 30 Hz PSR beam  This meets our goal for measuring the fission cross section of the 235 U isomer with a 10 ng sample.  Good prospects for other (n,  ) measurements.

Fission cross section measurements are underway for the AFCI program Extend program of Lisowski and that of Staples & Morley Measurements both at WNR and at Lujan  data from thermal to ~ 200 MeV Double Frisch-gridded ion chamber – from Hambsch (IRMM, Geel, Belgium) Data very soon

The LANSCE program in nuclear data attracts researchers from many laboratories GEANIE – LANL, LLNL, INL, Bruyères-le-Châtel, NC State FIGARO – LANL, BNL, Bruyères-le-Châtel N,Z – LANL, Ohio U DANCE – LANL, LLNL, INL, ORNL, Colorado School of Mines, FZK Karlsruhe, NC State, others LSDS – LANL, LLNL, BNL, Bruyères-le-Châtel, RPI Fission – LANL, INL, IRMM (Geel) Proton – LANL, Georgia Tech Others – MIT, Kentucky, Kyushu, Harvard,…

The LANSCE program is supported by several funding agencies NNSA - accelerator and experiments DOE - Nuclear Energy - Advanced Fuel Cycle Initiative DOE - Office of Science – Nuclear Physics LANL internal funds (LDRD)

Some improvements for the future (1) Improvements in Beam –More beam at WNR (factor of 4 to 6) from improvements in the ion source, better transmission and a longer macropulse length (= higher duty factor) »Permits shorter run time; more experiments »Permits larger micropulse spacing so that frame overlap is less of a problem  go to lower neutron energies At present with 1.8 microsecond spacing At 9 m  fram overlap at 130 keV and lower At GEANIE at 20 meters  600 keV At 90 meters  9.6 MeV –More beam at Lujan (factor of ~2) due to improvements in the ion source »More experiments »Possible shorter pulse length with same current  allows to go to higher neutron energies ( > 100 keV), now limited in resolution by the width of the pulse.

Some improvements for the future (2) More improvements in beam: PSR-to-WNR Fills in the region between Lujan and present WNR: 10 keV to a few MeV  of great importance to Advance Reactors and Weapons Much larger micropulse spacing (16 ms to 2.8 ms) New WNR target to enhance flux in the 10 keV to a few MeV region Increase in intensity over Lujan in this region by a factor of > 30

Some improvements for the future (3) Availability of radioactive samples through IPF Many more radioactive isotopes for experiments at DANCE and LSDS Close-by  relatively short-lived isotopes possible Improvements in instruments –GEANIE – higher efficiency HPGE detectors –FIGARO – complete array to 50 detectors –DANCE – include some HPGe detectors –(n,z) – more detectors to give larger solid angle, more angles –Fission – Mass, charge, energy detection for both fragments in coincidence –Lead Slowing-Down Spectrometer: Dedicated location (?beam line) – so assembly/disassembly not required each time –Integral experiments – like pulsed spheres?

Brief summary of LANSCE Capabilities Excellent timing for fast neutrons ( < 1 ns at WNR) High intensity for En 1 MeV (WNR) Energy range extends to ~ 600 MeV Low gamma-flash for fast neutrons (WNR) Many well-characterized instruments Many flight paths – used simultaneously Ability to access proton beam directly (e.g. LSDS) (Ability to do classified experiments) Many improvements planned in beam and instruments