center for the exploration of energy and matter the low ......low energy neutron source center for...

Low Energy Neutron SourceCenter for the Exploration of Energy and Matter

The Low Energy Neutron Source –C S d F PlCurrent Status and Future Plans

Paul SokolPaul SokolIndiana University

Thomas Rinckel , Roger Pynn, Helmut Kaiser, Warren Garfield,Helmut Kaiser, Warren Garfield, Dobrin Bossev, David V. Baxter

UCANS-II 2011 6 July 2011

Outline• Current Status

– Facility Operations• Accelerator• Target and Moderator• Instruments and Endstations

– Scientific and User Programs• SANS

• Future ProspectsFacility OperationsSANS

– Micelles– Viruses– Rocks

• Moderator DevelopmentR di ti Eff t

– Facility Operations• Accelerator

– Improved reliability– Full Power Operation– Performance upgrade

18 /100 A i• Radiation Effects• Radiography

– 18 MeV/100 mA operation

• Target and Moderator• Higher performance

moderators• Alternative target cooling• Alternative target cooling

• Instrumentation and Endstations• SESAME• Powder Diffractometer

i


• Test Beam Line• Radiation Effects• Radiography

The Low Energy Neutron Sourcelow-energy (p,nx) reactions (Ep<13MeV) in Be.

cold moderator (e g solid CH atcold moderator (e.g. solid CH4 at 1K<T<40K).

variable pulse width (from ~10 s to more than 1 0 ms)to more than 1.0 ms).

Accelerator•13 MeV Linac•~25 mA Peak Current•~2 mS pulse width

Instruments•SANS

•13 kW Average PowerTarget

•10x10 cm2

4 2 1013 /


SANS•SESAME

•4.2 x 1013 n/s

LENS AcceleratorAccelerator•13 MeV Linac•25 mA Peak Current•25 mA Peak Current•~2 mS pulse width•13 kW Average Power

4 MeV DTL6 MeV DTL

Operating at full peak power•Routine operation at 4 kW

•400 S pulse width•Short term operation at 6kW

25 KV Pulsed Ion Source3 MeV RFQ

4 MeV DTL •Short term operation at 6kW

RF System•3 ‐ 1.25 MWatt Klystrons•11 uF Cap (50 kJoules)

Switch tubes are biggest problem•Rated at 100 kV, operated at 85 kV•Break down ~every 6hrs


11 uF Cap (50 kJoules)•92 kV 5 amp Power Supply

y•New tubes (150 kV) ready to test

•Rinckel – Poster 21

Target, Moderator and Reflector

Nonlinear beam optics to provide even power distribution

Moderator•6 K Operation•Solid MethaneSolid Methane

Be Target•Design

•Original ‐ 4 mm thick Be •Current – 1.1 mm thick Be•Stopping distance 1.28 mm

•Water Cooling – 6 GPM•Peak Heat flux – 3 MW/m2


Peak Heat flux 3 MW/m•Target Power 12 kWFast Valve for Accelerator Protection

Rinckel Thursday 11:45

SANSRunning for Science Program

• PFP = 8.0 m

• SFP 1 0 m to 4 5 m• SFP 1.0 m to 4.5 m– Qmin = 0.06 nm‐1

– =2 0 nm 20 Hz– max=2.0 nm, 20 Hz• SCIENCE:

– Structure of surface‐functionalized nanoparticlesnanoparticles

– Complex fluids (surfactants, clay slurries, …)

Polymer networks


– Polymer networks

– Glasses/crystalization

LENS SESAME(Spin Echo Scattering Angle Measurement)p g g

Wollaston PrismFirst beam in April 2009Currently in commissioning phase

2/ 2/

Z

Currently in commissioning phase

sample

2

PolarizedGuide Sections

3 4

BENDER

mptor

AnalyzerSupermirror/ 3He

Tri. coils

SAMPLESTAGE Mode of operation

Shutter

1 2

Wall

3 4

Beam

dum

Detect •Transmission (SANS)

•Reflectometry(solids & liquids)


WallTMR PFP SFP


Micelles - aggregates of surfactant molecules self-assembled in aqueous solutions

Size of head group; length and number of tails; charge on surfactant; temperature; concentration; flow conditions

Applications:Rheological modifiers (paint detergents

surfactant; temperature; concentration; flow conditions

Rheological modifiers (paint, detergents, lubricants…)Oil field ( fracturing fluids)Hydrodynamic engineering (drag reducing agents)


Hydrodynamic engineering (drag reducing agents)Home and personal cares


40

100/60mM200/120mM

40

20.5C 30.0C

200/120mM(b)

20

30

nten

sity

(cm

-1) 400/240mM

600/360mM 800/480mM Rodlike A*exp(-(Q*r)2/4)/Q

(r=25A, A=0.65) Ellipsodal Model Fitting

20

30

40.5C 49.9C 58.8C Ellipsoidal Model

Fitting

nten

sity

(cm

-1)

10

Sca

tterin

g In

(a) T=20 5C

10

Sca

tterin

g In

0.01 0.10

Q (A-1)

(a) T 20.5C0.01 0.1

0

Q (A-1)

i ll lli id l•Micelles are Ellipsoidal•Size decreases with increasing concentration•Size decreases with increasing temperature


g p

Structure and Organization of RNA and Protein of BMVRNA and Protein of BMV

Brome Mosaic Virus SANS spectrum and radial density distribution

Hollow core

Inner

Iscosohedral Protein Shell di RNA

Inner core(RNA)

Outer surface(protein)

SAXS spectrum and radial density distributionsurrounding RNA SAXS spectrum and radial density distribution

Additional densityAdditional RNA4


Pressure Dependence of CO2 adsorption in Coal

100 I(Q)~ Q-1.87

3.8e-3psi (Dm=1.87, Ds=3.27)

250psi (Dm=1.87, Ds=3.39)

490 i-1)

CO2 adsorption in coal at 20.0oC (Pressure Up)

(a) 0.020

0 10

0.15

ity

Before HP cycling

10

490psi (Dm=1.87, Ds=3.25)

610psi (Dm=2.46) 705psi (Dm=2.64) 750psi (Dm=2.84) 810psi (Dm=2.84)835psi (D =2 84)g

Inte

nsity

(cm

-

I(Q)~ Q-2.840.010

0.015

^2 (c

m-1*A

-1^2

)

0 400 8000.05

0.10

Por

osi

Pressure (psi)

0 01 0 1

1I(Q)~ Q-3.27

835psi (Dm=2.84)

Sca

tterin

g

0.01 0.10.000

0.005

I(Q)*

Q

10.01 0.1Q (A-1)

)1()(2)( 22

0

2

dQQIQQinv

Q (A-1)Porod Invariant

I(Q)=A.Q-p + BVolume fractal->Surface fractal

0

Fully liquidation of CO2 occurs around 700psi in porous coal (830psi in bulk CO2); Porosity decreases as pressure up; Dm increases in large pores, Ds decreases in small pores as pressure up;

l di i i di b l i di i h i f b


Fractal dimension intending to be close 3, indicating a very rough interface between pore-matrix

Imaging


Moderator Research

10

100

400 K40 K10 K4 K

Significant interest in cold and very cold neutrons

0.01

0.1

1•Large scale structures•Fundamental Physics

S i i f i

• Validation/development of scattering kernels:0.0001

0.001

0.01 0.1 1 10 100 1000

LENS is ideal for exploring new materials and concepts

Validation/development of scattering kernels:– Methane phase II– VCN/UCN candidate material investigations– Total cross-section measurementsTotal cross section measurements

• Bench tests of new ideas/geometries– SNS poison burn-up issues

Be filter/reflector


– Be filter/reflector – Spin equilibration

Moderator Research at Moderator Research at LENS


Radiation Effects StudiesSecond target station optimized for radiation damage studies Electronics irradiationLow energy testing

1-10 MeV

Silicon

Base-Emitter saturation voltage (VBESAT)


Damage

Future PlansFuture Plans• Accelerator

– Improve reliability• Klystron Switch tubes

– Full Power Operation• Reduce losses

I d• Increase stored energy– More capacitors

– Long Term •Target– Long Term• Increase Energy (18

MeV)

•Target•Alternative Cooling•Gallium Loop


• Increase Power (100 mA)

Moderator Development•Higher performance moderators

•LENS, …•SNS, Lujan, ISIS, …

New Moderator Concepts


InstrumentationBring existing instrumentation

on line (SESAME)( )

Develop new capabilities

Multiplexed TOFDiffractometer

Test Beam Linecross sectionsemission time

L12 L2S

Diffractometeroptics studies

N I t t tiNew InstrumentationLong pulsed sources


Optimize FacilitiespCurrent TMR1

R di i EffRadiation Effects


10cm x 10cm Sample access

Develop ApplicationsDevelop user communities

Traditional UsesPhysicsChemistryBiology

New CommunitiesAnthropologyPaleontologyPaleontologyArt Conservation


Conclusions•• LENS is operationalLENS is operational

–– Regularly scheduled operation (4 kW)Regularly scheduled operation (4 kW)–– Multiple facilities availableMultiple facilities availableMultiple facilities availableMultiple facilities available

•• SANSSANS•• SESAME (real soon now)SESAME (real soon now)•• Radiation EffectsRadiation Effects

Radiograph /TomographRadiograph /Tomograph•• Radiography/TomographyRadiography/Tomography

•• Future FocusFuture Focus–– SourceSource

I li bilit d PI li bilit d P•• Improve reliability and PowerImprove reliability and Power•• Better ModeratorsBetter Moderators

–– InstrumentationInstrumentation•• New capabilitiesNew capabilitiesNew capabilitiesNew capabilities•• New techniquesNew techniques

–– ApplicationsApplications•• Scientific studiesScientific studies


•• Moderator DevelopmentModerator Development

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