report on usa experimental activities

Report on USA Experimental Activities

Donald L. Smith

WPEC 2004

Introduction

• Present report is derived entirely from material presented at the annual CSEWG meeting on 4 - 6 November 2003

• Contributed laboratory reports- ANL, NIST, LANL, and RPI

• Potential resources in USA for applied experimental nuclear data studies- ATLAS, Univ. of Notre Dame, Univ. of Kentucky (Lexington)

Background

• Reports contributed to CSEWG by experimental programs are voluntary (not required by any funding organizations)

• Much of the experimental work in the USA of potential importance from a nuclear data viewpoint is done in government and university laboratories under a variety of funding auspices … difficult to track work

Argonne National Laboratory

• The ANL nuclear data program has two experimental components that involve collaborative projects done elsewhere- Heavy-ion and structure physics (ATLAS)- Neutron activation cross sections (IRMM)

• A brief description of the heavy-ion work is given here while the neutron cross section work is discussed elsewhere (IRMM)

• Principal Investigator is Filip Kondev (DLS is a retired collaborator)

ANL: Continued - 1

• Properties of nuclear K-Isomers in A∼180 mass region (GS*)

• Properties of nuclei at proton drip line (GS & FMA*)- 181Pb, 181Tl, and their daughters- Studies of odd-odd Au isotopes- Radiative capture in HI fusion (e.g., 90Zr+92Mo, 90Zr+89Y)

* GS = Gammasphere; FMA = Fragment Mass Analyzer

ANL: Continued - 2

• Spectroscopy of heavy nuclei- Decay data on 251Cf- Decay data on 253Es- Lifetimes of very long-lived 245,246Cm & 239Pu

• These experiments contribute to a nuclear database of importance mainly for nuclear structure evaluators (ENSDF)

• Strong interest on the part of basic nuclear physics community (e.g., astrophysics)

• Following slides from ANL talk at CSEWG

ANL Slides

5

Pioneering Science andTechnology

Office of ScienceU.S. Department

of Energy

Courtesy to John Becker, LLNL

6



of Energy

Nuclear IsomersANL/LANL/LLNL Collaboration

Phys. Rev. Lett. 87 (2001) 072503

Texas/AFRL/SNL CollaborationPhys. Rev. Lett. 82 (1999) 695

Energy in 1 g of the “charged up” 178mHf equivalent to 500 lbs of TNT!

Results are very controversial, but the stakes are enormous!

The Nuclear Data input – vital!

7



of Energy

Nuclear Isomers – cont.

J.J. Carroll et al., Hyp. Int. 135 (2001) 3

8



of Energy

Nuclear Isomers – cont.176,177Lu: no stable beam/target combination to produce them in HI,xnTool: deep inelastic and multi nucleon transfer reactionsExperiment: 136Xe beam on enriched 176Lu target @ 6 MeV/A (~20% above

the Coulomb barrier)/Pulsed beam & Gammasphere

Submitted to Phys. Lett. B

New 3- and 5-qp IsomersPossibility of β− branchTransition strength – K robustness

9



of Energy

Lifetimes of very long lived actinide isotopesConventional techniques are compromised when the lifetimes are long, e.g. hundreds and thousands of yearsMass spectrometry approach - systematic uncertainties are unknown or potentially large

Our Approach

Mass separated samples (1975!)Parent/daughter activityAlpha counting techniqueApplied to 245,246Cm and 239Pu

T1/2=4747 (46) years / Compared to values ranging from T1/2=2300 up to 6620 years

250Cf 246Cm 242Puα α13 y 4747 y

α5105 y

National Institute for Standards and Technology

• Neutron scattering from hydrogen- H(n,n) angular distribution is being measured at 15 MeV at Ohio University (NIST/LANL/OU)- Needed to improve quality of the database near 15 MeV for the H(n,n) standard evaluation

• Coherent neutron scattering length studies- Hydrogen measured to 0.05% accuracy- Deuterium measured to 0.06% accuracy- 3He measured to 0.1% accuracy- All measurements performed at NIST reactor

NIST: Continued - 1

• Neutron fluence calorimeter- Work continues to check calibration accuracy (goal is ∼ 0.1%)- Accuracy of calibration depends strongly on understanding all sources of systematic error- Small amounts of power (< 1µW) involved- Stored energy in target material defects are a potential problem area in calorimetric studies- Measurements with a 6Li absorber and 3He cryogenic target are being undertaken

NIST: Continued - 2• 6Li(n,t) experiment

- Measured cross section at ∼ 5 meV with a cryogenic calorimeter (∼ 0.4% accuracy)

• Iron spherical shell transmission studies- Measurements completed using 15N(p,n) and D(d,n) neutron source reactions and various laboratory angles from 0º to 135º

• Neutron transport through shells- Scoping calculations for various materials have been performed and compared with integral nuclear data to indicate where further differential data development work is needed

Los Alamos National Laboratory• Neutron measurements at LANSCE

involve the use of several instruments- GEANIE, FIGARO, DANCE, “n-Z”, Lead SDS

• Characteristics of experimental program- Many collaborators (universities and nat’l labs)- Wide range of elements, isotopes, reactions- Wide energy range (En = thermal to >200 MeV)- Neutron and photon measurements- Collaboration with theorists and evaluators

• Following slides from LANL talk at CSEWG

LANL Slides

Some recent cross section results from GEANIE/WNR:(n,xγ) and (n,x-ray) to infer cross sections

0.5 MeV < En < 200 MeV

• 193Ir(n,n’γ)193m2Ir Fotiadis, et al.,next slide• n+89Y for En < 20 MeV Garrett, UCRL-ID-153190 (2003)• 75As(n,2n)74m,gAs Younes, UCRL-ID-154061 (2003)• 238U(n,xnγ) Fotiadis, Phys. Rev. C, in press• 235U(n,n’)235mU Younes, UCRL-ID-151071 (2002)• 238U(n,f) x-ray yields Granier, Phys. Lett. B, submitted

GEANIELLNL/LANL

193Ir(n,n')193mIr

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 2 4 6 8 10 12 14 16 18

En (MeV)

σ(m

b)

Crucial Region for Fission Neutrons

Bayhurst 75 - Experiment

GNASH 98 - Evaluation

GEANIE 03 - Experiment+Model

Arthur/Little 79- Evaluation

Hermann 96- Evaluation

New GEANIE data significantly improve the 193Ir(n,n’)193mIr cross section database

GEANIELLNL/LANL

X rays from Neutron-Induced Fission of 238U give elemental yields

238U(n,f) fission product mass and charge distributions as a function of incident-neutron energy.Measurement of x-rays and gamma-rays with GEANIE following neutron-induced fission at WNR allow a detailed study of the fission products as a function of incident neutron energy.

I

Xe

Cs

Ba La

CePr

Plot of the data and fit to the x-ray spectrum showing 7 fission product elements from 238U neutron-induced fission.

Ex-ray(keV)

coun

ts/b

in

Some recent cross section results from FIGARO/WNR:neutron-emission spectra

1 MeV < En < 200 MeVFission Chamber in beam• 238U(n,f): Efn Ethvignot, Phys. Lett. B (in press)• 235U(n,f): Efn Ethvigot, a.i.p• 235U(n,f): Efgamma Nelson, a.i.p• 238U(n,f): nu-bar Ethvignot, paper in prep.

Gamma-ray trigger (HPGe or BaF2)• Si(n,n’gamma) Rochman, submitted to NIM• Fe, Ni, Mo, Pb Data taken

28Si(n,n’)

Neutron emission from neutron reactions is studied as a function of incident neutron energy

29Si

28Si + n(target)

En

2+4+

0+

ρ(Jπ,Ex) n'

-8.473Trigger

We compare our results with GNASH and EMPIRE calculations

New data for helium production from neutrons on 58Ni show deviations from LA150

58Ni(n,xα)

0

50

100

150

200

250

300

350

400

450

0 10 20 30 40 50 60 70 80 90 100En(MeV)

Cro

ss S

ectio

n (m

b)

ENDF/B-VI

LANSCE data

LA150

Some recent cross section results from DANCE/MLNSC: neutron capture cross sections

1 eV < En < 200 keV

Runs done with 141 crystals• Au(n,γ) standard• 234, 235, 236, 238U(n,γ) cross section (stewardship)• 151Sm(n,γ) cross section (astrophysics)

Runs done with 159 crystals• Au(n,γ) standard• 151Sm(2003) astrophysics• La, Cu, Mn, Co(2003) astrophysics, systematics

Preliminary Results: 234,236U Resonances

Raw Energy Spectra

Resonances fit using SAMMY code• Parameters determined from Au resonances• Teff = 300° (Doppler Broadening)• ∆L = 0.0109 m (Moderator thickness)• ∆Tx = 0.390 µsec (Exp. Tail parameter)• TE = 0.019 µsec (Gaussian width param.)

Neutron Energy (eV)

Cro

ss S

ectio

n (b

arn s

)

Sammy Fit, 234U

Neutron Energy (eV)

Cro

ss S

ectio

n (b

arn s

)

Sammy Fit, 234U

Neutron Energy (eV)

Cro

ss S

ectio

n (b

arns

)

Sammy fit 236U

Neutron Energy (eV)

Cro

ss S

ectio

n (b

arns

)

Sammy fit 236U

236U

234U

0.5 mg of 151Sm(n,γ) – TOF spectra show capabilities of DANCE

A Lead Slowing-Down Spectrometer is under development, driven by 800 MeV protons from the PSR

Neutron trajectories following the interaction of 1 proton with the tungsten target in the lead cube

Lead Slowing-Down Spectrometer: To measure fission cross sections of ultra-small samples

• Effort motivated by interest in measuring the fission cross section of isomers and small samples of actinides

• Calculations show that cross section for 235mU is significantly different than for ground state

• Experiments are in collaboration with LLNL, RPI and CEA/DAM

Fission cross section of 235U and 235mU

First excited state of 235U is produced in decay of 239Pu

• 235mU– 26 min half-life– 73eV– Decays by internal conversion– 99% of 239Pu decays populate

235mU– 5 gm of Pu will produce 10ng of

235mU• Fast extraction of 235mU will be

required• To measure this small cross

section, it is necessary to increase the neutron flux by using a lead-slowing down spectrometer (LSDS)

Otherlevels

235U

239Pu

99%

73eV

7/2 -1/2 +

α-decay

1/2 +

0

{τ1/2 = 26 min

235mU is produced in the α-decay of 239Pu

We have characterized the time-energy correlation and measured the resolution in capture resonances

Simulation: <En> = K / (t + to)2

with resolution, ∆E/E~ 30%

The LANSCE program in nuclear data involves many laboratories

• GEANIE – LANL, LLNL, Bruyères-le-Châtel, NC State• FIGARO – LANL, Bruyères-le-Châtel• N,Z – LANL, Ohio U• DANCE – LANL, LLNL, ORNL, Colorado School of

Mines, FZK Karlsruhe• LSDS – LANL, LLNL, Bruyères-le-Châtel, RPI• Proton – LANL, Georgia Tech• Others – MIT, Kentucky, Kyushu, Harvard,…

Rensselaer Polytechnic Institute

• Experimental work is performed at the Gaertner Linac Laboratory in Troy, NY

• Program focus is on neutron transmission and capture measurements as well as studies carried out with the RPI Pb SDS

• Present report highlights experimental measurements, data analysis, and instrumentation development work at RPI

• Following slides from RPI talk at CSEWG

RPI Slides

Measurements Completed This Year

• Cd– Epithermal transmission and capture measurements

(5-1000 eV), thick samples.– This completes our measurements for Cd.

• Rh– Thermal transmission and capture (0.002-20 eV)– Epithermal transmission and capture (1-1000 eV)

Analysis in Progress

Sample Status

Gd Analysis in final stages

NbSAMMY fits for thermal and epithermal capture and transmission are almost complete

Nd Completed

Hf Completed

Hf And Nd Measurements and Analysis

• SAMMY fits to Transmission and Capture Data– Includes new fits to the resolution functions and error

analysis that includes this function.– Simultaneous fits of all data sets, Typically:

• Several samples for thermal transmission and capture measurements (0.005 eV - 20 eV)

• Several samples for epithermal transmission and capture experiments (1 eV - 500 eV)

• In the case of Hf, enriched liquid samples Hf-176 and Hf-178 were also used

• Data and Analysis details soon available in PhD theses of Devin Barry (Nd) and Mike Trbovich(Hf).

Nd Epithermal Data

Nd Transmission and Capture Yield 280-400 eV

Nd 4.3 eV Resonance

Hf Epithermal Data

Hf Transmission and Capture Yield 95-115 eV

Hf Thermal Data and fits

HF – Comparison With ENDF Parameters

New Capabilities

• Transmission Measurements at 100 m flight station with a large Neutron Detector (~104 cm x 70 cm)

– Allows high energy and resolution transmission and spectra measurements in the energy range 0.5-10 MeV.

– Detector characterization and design completed.

New Detector

Potential Experimental Resources• A report based on presentations from a few labs

that routinely contribute to CSEWG is misleading w.r.t. assessing USA nuclear data capabilities

• Extensive nuclear research is performed in many universities and government labs under various funding auspices (DOE, DOD, NSF, etc.)

• A sampling of three laboratories that either do contribute to the USA nuclear data effort, or have the potential to do so, are featured here: 1) Argonne ATLAS facility; 2) Univ. of Notre Dame; 3) Univ. of Kentucky (Lexington)

• Following slides from DLS talk at CSEWG

Argonne ATLAS Facility (1)

Location: Physics Division, Argonne National Laboratory, Illinois

Nature of Facility: Heavy-ion accelerator (heavier than an electron and extending up to the trans-plutonium regime!)

Current Emphasis: Nuclear structure and nuclear reactions occurring far from the line of stability, exotic reactions (for astrophysics, etc.)

Major Sponsor: DOE (Office of Science)


Key Features: Two distinct ion injector facilities … accelerates particles to 17 MeV/nucleon … extensive sample preparation capabilities … extensive beam analysis and radiation detection instrumentation

Technical Staff: Experienced in-house scientists and support personnel … a user facility for researchers around the world … grad students … post docs

History: Operational for about 20 years … continuously upgrading capabilities … programs evolve with changing national (int’l) priorities


Nuclear Data Applications: Rich source of nuclear structure data … Accelerator Mass Spectrometry (AMS) applications … solving key questions in astrophysics … candidate site for RIA facility

Note: AMS will play a much bigger role in applied nuclear energy studies in the future and ATLAS is a key resource in this growing area of nuclear technology

University of Notre Dame Accelerator Laboratories (1)

Location: Notre Dame Campus, South Bend, IndianaNature of Facility: Three Van de Graaff accelerators

(JN – 1MV, KN – 4 MV, FN Tandem – 10 MV) offer a wide range of nuclear beam options

Current Emphasis: Astrophysics, nuclear structure and reaction mechanisms, nuclear processes initiated with radioactive nuclear beams

Major Sponsor: National Science Foundation


Key Features: Wide range of nuclear beam types and energies … extensive sample preparation facilities … extensive nuclear measurement instrumentation

Technical Staff: Experienced faculty and support personnel … grad students … post docs

History: Laboratory in operation for several decades … co-developer of the famous Browne/Buechner magnetic spectrograph … strong player in nuclear astrophysics … acquired JN and KN accelerators from de-commissioned laboratories in Canada


Nuclear Data Applications: Large contributor to nuclear astrophysics … facilities could be used for a wide range of nuclear structure and nuclear reaction data measurements applicable to nuclear energy development

Note: An important asset of this laboratory is its extensive network of scientific collaborators in the U.S. and abroad

University of Kentucky –Lexington L.E. Nuclear Physics Laboratory (1)

Location: U of K campus, Lexington, KentuckyNature of Facility: 7 MV accelerator (modified from

the original Van de Graaff design)Current Emphasis: Nuclear structure and nuclear

reaction studies in the MeV region using (CP,n), (CP,nγ), (n,n’ γ), etc., reactions on medium and heavy nuclei … properties of low-lying states

Major Sponsor: National Science Foundation


Key Features: Various available gas and solid target arrangements involving 7Li, 3H, and 2H can be used to produce wide range of neutron energies … neutron and gamma-ray spectrometers

Technical Staff: Experienced faculty researchers … grad students … post docs

History: This laboratory has been in operation for several decades and has been very productive in several areas, especially neutron-induced gamma-ray production processes in the MeV region


Nuclear Data Applications: Rich source of nuclear structure data for low-lying levels of stable nuclei … facility could be used for various L.E. nuclear reaction studies and nuclear applications testing

Note: Studies of explosives detection by neutron transmission measurements have been performed at this facility in collaboration with scientists from other institutions … however, one concern is the aging of experienced core staff

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