my great russian adventure & a little bit of science …s.s. hecker: the story of pu mountain,...

LLNL-PRES-671075

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC

My Great Russian Adventure & A Little Bit of Science

or How I went from Fond du Lac

to Moscow and Back

JG Tobin

University of Wisconsin-Oshkosh

and many, many collaborators

Livermore, CA, USA

Date 15 Nov 2015

LLNL

St. Basil’s

Red Square

Moscow

University of Wisconsin-Oshkosh LLNL-PRES-671075 2

Overview of talk Perspective

A little bit of History

Nonproliferation issues

Russian-US Pu Workshops

JGT’s Pu Experiments

Digression: DOE Facilities, Synchrotron Radiation & XAS

Andrey Kutepov calculations

Digression: Inverse Photoelectron Spectroscopy

Digression: Mayak disaster

Mikhail Ryzhkov calculations

Alex Mirmelstein and Neutron Scattering

Summary


Ancient History: born and raised in FdL

and went to the Springs for High School

St. Mary’s Springs ~1910

St. Mary’s Springs Now

Lake Winnebago

Fond du Lac

OK,

so I’m

old

but

not

quite

that

old…


Perspective:

How jgt fits into the big picture

jgt is just a flea on the hair of the tail of a very large dog…..

World diplomacy

International relations

Non-Proliferation


Timeline 1

95

6

Bu

da

pe

st,

Hu

ng

ary

19

68

Pra

gu

e S

pri

ng

19

80

So

lid

ari

ty/P

ola

nd

19

89

Be

rlin

Wa

ll F

all

s

19

91

So

vie

t U

nio

n

Dis

so

lve

s

Subsequently, there

were concerns about the

loss of control of nuclear

materials and people

with nuclear expertise…

Knocking

down the

wall


Materials…An Example from Kazakhstan S.S. Hecker: The story of Pu Mountain, Bull. At. Sci. 69, 1(2013)

This is about the clean-up at Semipalatinsk test site in Kazakhstan.

Also see “Megatons to Megawatts” about buying Russian U at

http://nnsa.energy.gov/mediaroom/pressreleases/megatonstomegawatts


People ASC/Russian Science &Technology

Cooperative Program

• DOE/ACSI funds contracts with

Russian Defense Lab scientists doing

basic research

• The Gordon-Ryabev agreement called

for one million dollars per laboratory to

be available each year to support these

collaborations.

• The desired outcome is to draw new

scientists into the collaborative efforts.

• http://nnsa.energy.gov/aboutus/ourprog

rams/defenseprograms/futuresciencean

dtechnologyprograms/asc/ascrussiacoll

aboration-0.

In parallel with Pu Workshops started

by Sig Hecker.. .. ..Outreach by US

Defense Labs.

http://nnsa.energy.gov/aboutus/ourprograms/defenseprograms/futurescienceandtechnologyprograms/asc/ascrussiacollaboration-0









Russian-US Pu Workshops:

This effort was lead by Sig Hecker, an Emeritus

Director of Los Alamos National Lab Tobin and Hecker with Russian

Scientists at a Monastery

outside Sarov, 2007

Tobin Hecker

9 Meetings in Russia during 2001-2013


Meetings at Sarov:

Flew into Nizhniy

Novgorod and

played tourist

Volga River in NN

NN Kremlin Museum

Tobin and T-34

Church Artwork outside Sarov


There was

also

business

Poster from

Sakharov’s

House in

Sarov

Tobin with

mock-up of

100 Megaton

bomb in Sarov

Museum

So, back to the science…


Meanwhile, we’d been busy… Pu Experiments at the Advanced Light Source

in Berkeley, CA The ALS is a 3rd generation synchrotron radiation

source.

In some ways,

the most important

result was from XAS,

or X-ray absorption

spectroscopy.

But first, a

digression.. .. ..


The Office of Basic Energy Science within the Department of

Energy has a number of magnificent user facilities


I’ve had the good fortune to work at four of them.. .. ..

Stanford

Synchrotron

Light Source,

Stanford, CA

Advanced Light Source,

Berkeley, CA

Advanced Photon Source,

Chicago, IL

Spallation Neutron Source,

Oak Ridge, TN


Synchrotron Radiation Light Sources The ALS, APS and SSRL are really

just very big and very expensive x-

ray tubes

It’s all about electron acceleration.

In an x-ray tube, the high energy

electrons smash into a cathode,

generating a line spectrum

corresponding to the target

material and a bremstrahlung

continuum from the deceleration.

In the synchrotron source,

magnetic fields deflect the highly

relativistic electrons, causing the

emission of x-rays.


Whenever the electron beam is deflected (accelerated), photon radiation is emitted.

The insertion devices, especially the undulators, are almost a single pass laser.

BTW, I did my first experiment at SSRL in 1979 and most recent in 2014.. .. ..

Bldg 120 at SSRL


Comparison of Processes:

BIS, XPS and XAS

XPS samples the occupied DOS or Valence Band (VB)

BIS and XAS sample the unoccupied DOS or Conduction Band (CB) Photon absorption and emission:

electric dipole transitions with Δl = +/- 1


X-ray absorption spectroscopy (XAS)

Beer’s Law for

visible light and

aqueous

solutions

A = abc

A = Absorbance

a = absorptivity

b = path length or

sample thickness

c = concentration

of the solution

A = log10 (1/T)

abc = log10 (I0/I)

All absorption experiments are essentially the same

I0 I

Transmittance

T = I/I0

S

a

m

p

l

e

X-ray Absorption I = I0 e-μx

μ = absorption coefficient

x = sample thickness

μx = -ln (I/I0) = ln(I0/I) ln(z)/log10(z) =1/ log10 (e) = 2.303


X-ray absorption spectroscopy (XAS)

The ideal experiment

is in transmission

mode, but

sometimes that can’t

be done…

Total fluorescence

yield (TFY) is less

surface sensitive

than total electron

yield (TEY).

TEY can also be

done with electron

collection with a

channeltron.

Tunable hv source (Synchrotron radiation)


X-ray absorption

spectroscopy

(XAS) • Notice how the Uranium

and Plutonium results

are different. This is

caused by the 5f states.

• Our theory did not treat

the spin-orbit splitting

in the 5f’s properly, but

there was a theoretician

in Snezhinsk (VNIITF)

who did…


Pu Electronic Structure

with the Russians VNIITF in Snezhinsk near

Ekaterinburg.

The Czar’s family was killed

at Ekaterinburg.

Statue of Lenin

Tobin

City Square in

Snezhinsk


The meetings in Snezhinsk were held in

a self-contained meeting center on the

outskirts of the city…

Group Photo from September, 2011

Tobin


Digression: Mayak Disaster

#3 nuclear contamination disaster after Chernobyl and Fukushima

The nuclear complex is located 150 km south-east of Ekaterinburg, between the towns of Kasli and Tatysh, and 72 km northwest of Chelyabinsk.

I found out about this because my eldest child wrote a poem in High School about Chelyabinsk…

But we shouldn’t be too self righteous: there’s quite a mess at places like Hanford in eastern Washington State.

Ekaterinburg

Snezhinsk

Kasli…….

Chelyabinsk


http://nnsa.e

nergy.gov/sit

es/default/fil

es/nnsa/inlin

efiles/LLNL-

06.pdf

Andrey Kutepov’s

Calculations: Treated the spin orbit

splitting of the 5f’s in a

more fundamental way.


Andrey’s Theory also

helped us explain older

results such as BIS or Bremsstrahlung

Isochromat Spectroscopy.

This is a type of high energy

inverse photoemission… Just a XPS can provide a measure

of the occupied density of states,

within certain approximations, BIS

can provide a measure of the

unoccupied density of states or

UDOS.


Digression:

Inverse Photoelectron Spectroscopy (IPES), including

Bremstrahlung Isochromat Spectroscopy (BIS) & Resonant IPES or RIPES

IPES hv = KEe - HF + Φ

XES KEe > BE (core) & hv ≈ BE (core)

Wavelength

selection in

detection of hv Can also do XES with

photon in & photon out

Mono-energetic

beam of electrons


Digression: XES and IPES, BIS &RIPES

Some were done at the ALS and some at LLNL

BIS & RIPES:

XES 350

(VG Scienta)

Photoelectron Spectroscopy, with spin

and without spin (multichannel)

SRPES:

Phoibos 150 with Mott detection (Specs)

Fano Spectroscopy with the chirally

configured He UPS sources

XPS with the X-ray tube, AlKα and MgKα

Sample

handling

system for

actinides

• The goal is to perform

equivalent experiments

upon more highly

radioactive samples at

LLNL than can be used

at the ALS.


Another problem that was bothering us

was the change in electronic structure

from the atom to the bulk in Pu…

Atomic Configuration

—[Rn-86] 7s2 7p0 5f6 6d0

Bulk Configuation

—[Rn-86] 5f5 (7s7p6d)3

The 6d’s are the key to the bonding.

We needed a way to connect these two limits.

Once again, we turned to VNIITF …


Actinide NanoScience: Pu Clusters

from VNIITF in Snezhinsk and the

Urals-Russian Academy of Science

(URAS) in Ekaterinburg…MV Ryzhkov.


Evolution of Pu

electronic structure 5f population

• decreases linearly with 3√N, with N = # atoms…3D evolution

• connects the atomic/dimer regime (n5f = 6) to the bulk regime (n5f = 5)

7p states

• high degree of delocalization,

• correlate with the 5f states.

6d and 7s state occupancies

• almost mirror images of each other

• no simple linear relationship

• suggests the transfer of electronic density from the 7s into the 6d 6d = bonding (Cooper)

net transfer of electronic density;

• 5f/7s 6d/7p.


Ryzhkov’s earlier calculations have also helped us

understand the role of covalency in the bonding of UO2, the

most important nuclear fuel for the generation of

electricity…Theory in orange below. UO2 has

covalency in both

the 5f’s and 6d’s,

but the more ionic

UF4 only has

covalency in the

6d’s.

I’ll save the

details of this for

another day…


Another aspect of that

contract was experimental

work at the Spallation

Neutron Source (SNS) on

site at the Oak Ridge

National Lab (ORNL).

…A. Mirmelstein of VNIITF

…CeNi: surrogate for Pu

…Neutrons are a new trick

for jgt

jgt


Neutron Scattering of CeNi at the

Spallation Neutron Source in Oak Ridge

So the detector is many time the size of a human being…


Summary of talk Perspective

A little bit of History

Nonproliferation issues

Russian-US Pu Workshops

JGT’s Pu Experiments

Digression: DOE Facilities, Synchrotron Radiation & XAS

Andrey Kutepov calculations

Digression: Inverse Photoelectron Spectroscopy

Digression: Mayak disaster

Mikhail Ryzhkov calculations

Alex Mirmelstein and Neutron Scattering

Summary


Collaborators and Acknowledgements VNIITF-Snezhinsk-A.L. Kutepov, A. Mirmelstein

Russ. Acad. Sci.-Urals-Ekaterinberg-M.V. Ryzhkov

LBNL-Berkeley-D.K. Shuh, CH Booth, R. Qiao, W.L. Yang, K. Heinzelman, E. Rotenberg, S. A. Morton,

and P. Olalde-Velasco

SSRL-Stanford- Dimos Sokaras, Tsu Chien Weng

LLNL-Livermore-S.-W. Yu, B.B. Ebbinghaus, M.T. Butterfield, N.E. Teslich Jr. , R.A. Bliss, A.K.

McMahan, B.W. Chung, K.T. Moore, M.A. Wall, A.J. Schwartz, P. Söderlind,

A. Landa, J. C. Crowhurst and W. J. Siekhaus

LANL-Los Alamos-J.M. Wills, J. Terry, R. K. Schulze, J. D. Farr

ORNL-Oak Ridge-R.G. Haire, A. Podlesnyak, A. M. dos Santos, G. Ehlers, O. Kerbel, V. Matvienko,

A.S. Sefat, B. Saparov, G. Halder, A.I. Kolesnikov,

Missouri U. of Sci. and Tech.-Rolla - T. Komesu, G.D. Waddill

PSI-Switzerland –B. Delley

Diamond (UK)- G van der Laan

Max Planck-Germany -S. Sharma, J. K. Dewhurst

Funding provided by LLNL, OBES, NNSA and DOE is gratefully acknowledged.


It’s been a blast! Sarov 2013 Group Photo

Tobin

my great russian adventure & a little bit of science …s.s. hecker: the story of pu mountain,...

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