Experimental Capabilities for Applied Nuclear …bang.berkeley.edu/wp-content/uploads/DANON_LBNL_2015.compressed-1.pdfExperimental Capabilities for Applied Nuclear Science at RPI

1nacThe Gaerttner LINAC Center

Experimental Capabilities for Applied Nuclear Science at RPI

Professor, Director Gaerttner LINAC Center Nuclear Engineering Program Director

Department of Mechanical, Aerospace and Nuclear EngineeringRensselaer Polytechnic Institute, Troy, NY, 12180

Yaron Danon

DOE Nuclear Data Needs and Capabilities for Applications (NDNCA) workshop, LBNL, May 27-29, 2015


RPI Faculty

Prof. Yaron Danon - LINAC Director

Prof. Li Liu

KAPL

Dr. Greg Leinweber

Prof. (Emeritus) Robert C. Block

Dr. Devin Barry

Dr. Michael Rapp

Dr. Tim Donovan

Mr. Brian Epping

Dr. John Burke

Technical Staff

Dr. Ezekiel Blain

Peter Brand

Michael Bretti

Matt Gray

Azeddine Kerdoun

Graduate Students

Adam Daskalakis

Brian McDermott

Adam Weltz

Nicholas Thompson

Kemal Ramic

Carl Wendorff

Amanda Youmans

Jesse Brown

RPI Nuclear Data Group

BOLD= researcher or graduate students supported by NCSP

This work was supported by the following DOE grants: KAPL/BMPC/NCSP POs 103971, 7013680, DE-NAOOO1814,DE-FG03-03NA00079, DE-FG52-06NA26202, DE-FG52-09NA29453.


Overview• The Gaerttner LINAC Center at RPI

• Capability Matrix

• Measurement Capabilities and Examples– Thermal Region: Transmission, Capture, Fission, (S(a,b) at SNS)

– Resolved Resonance Region: Transmission, Capture, Fission

– Unresolved Resonance Region: Transmission, Capture

– Fast Neutrons: Transmission, Scattering, Prompt Fission Neutron Spectrum

– Lead Slowing Down Spectrometer: Fission, (n, alpha), (n, p), Capture

– Prompt fission neutrons: The gamma tagging method

The target room


Why Should We Care About Nuclear Data?

Nuclear Data(Uncertainty)

Geometry Data

ComputationalMethods (Physics)

(Uncertainty??)

ResultsAccuracy??

Reactor Physics Calculations

• Effective neutron Multiplication factor• Neutron flux• Burnup• Kineticswww.llnl.gov

The Shippingport Reactor (Critical in 1957)http://www.pabook.libraries.psu.edu/palitmap/Shippingport.html


Nuclear Data Lifecycle (Danon’s view)

Application Driven

Evaluation ValidationDifferential

Experiments

Integral Experiments

Evaluated Data File

ENDF/B-VII.1

Critical BenchmarksAt RPI

Publication(s)

User Needs

Publication(s) Publication(s)

Publication(s)

$$ O

ther

Users

Appropriate Exp only

Applications


Where is the RPI LINAC ?• It is on the highest point in Troy, NY

LINACFlight

Stations

NESOffices

RPI Campus


RPI LINAC History• The RPI LINAC started operation in December 1961.• Working “continuously” since.

Graduated over 170 students who utilized the LINAC as part of their PhD

thesis research

Many years of accumulated experience

September 1997- LINAC was designated as Nuclear Historic Landmark by the American Nuclear Society

2014 - Started a major refurbishment and upgrade project


The RPI LINAC Facility

O FFICE

O FFICE

O FFICE

O FFICE

O FFICE

O FFICEO FFICEO FFICEO FFICE

SERVICE RO OM

BUTLER

BR

BR

SHO P AREA

BUILDING

HO T

LABORATO RY

DARKROO M

CO NTRO LROO M N EEP LAB

STO RAGE

ROO M

ROO M

TARGET

ACCELERATOR

ROO M

ROO MMO DULATOR

N ICE

LAB

ROO M

TARGET

ACCELERATOR

ROO M

N

GAERTTNER LINAC LABORATORY

INSTITUTERENSSELAER POLYTECHNIC

N



HO T

ROO M

TARGET

ACCELERATOR

ROO M

N ICE

LAB

ROO M

TARGET

ACCELERATOR

ROO M

25-METER

STATION

100-M ETER 250-M ETER STATION

N



N



N



30 PO RT

EN ERGY

AN ALYZIN G

MA GNET

He FLIGHT PATH

15-METER

D ETEC TORTRAN SMISSION

CAPTUREDETECTOR

DETECTOR

TRANS MIS SIO N

AUXILLARYEQ UIPMENTROO M

Bent/T il t

Focus

SPECTROMETER

LEAD SLOWING DOWN

EAST

45-METER STATIONSTATION

WEST

Neutron Production Target

Large Target Room

Detection Stations at:15m to 250m

Lead Slowing Down Spectrometer

Electron LINAC


LINAC Specifications 2015Three Sections

(Low Energy Port)Nine Sections

(High Energy Port)

Electron Energy

5 to 25 MeV 25 to over 60 MeV

Pulse Width 6 to 5000 ns 6 to 5000 ns

Peak Current

3A (short pulse: 6 to 50 ns)400 mA (long pulse: 50 to 5000 ns)

3A (short pulse: 6 to 50 ns)400 mA (long pulse: 50 to 5000 ns)

Average Power

10 kw@ 17 MeV, 5000 ns >10 kw@ 60 MeV, 5000 ns

Peak Dose Rate

>1011 Rads/sec (in Silicon) n/a

NeutronProduction

n/a ~4 X 1013 neutrons/sec

PulseRepetition

Rate

Single pulse to 500 pps (short pulse)Single pulse to 300 pps (long pulse)

Single pulse to 500 pps (short pulse)Single pulse to 300 pps (long pulse)


Capability Matrix and Development

10-3 10-2 10-1 100 101 102 103 104 105 106 107

PAC

BBT/PAC C6D

6 Capture Detector

ETT

LSDS fission / fragment dist.PFNS

Fast/LiGlass ArrayBT

BBT/PACMultiplicity Detector

Fission

PAC 100m LiGlass Detector

Under Development

BBT

ETT

BT

BT

BBT

ETT

Scattering

Capture

Neutron Energy [eV]

Transmission

15m LiGlass Detector

25m/30m LiGlass Detector

250m EJ301

Multiplicity Detector

Muliplicity Detector

EJ301 Array

RPI LINAC - Nuclear Data Measurement Capabilities 2015

BBT/PAC/BBT

ETT

TargetsETT- Enhanced Thermal TragetBBT - Bare Bounce TargetBT- Bare Target on AxisPAC - PacMan Target




New

New


Neutron Production TargetsEnhanced Thermal Target (ETT)Bare Bounce Target (BBT)

PACMAN target


Detectors

Transmission

Capture/multiplicity

ScatteringPFNS

25m

30m

45m


Current Activity• Time of flight measurements

– Resonance Region• Capture (0.01 eV – 2 keV)• Transmission (0.001 eV – 100 KeV)• Capture to fission ratio (alpha)• keV capture detector• Neutron scattering (E<0.5 MeV)

– High energy (0.4-20MeV)• Scattering (30 m flight path)• Transmission (100m and 250m flight path)• Prompt Fission Neutron Spectra

– High accuracy total cross section measurements using filtered beam• Lead Slowing Down Spectrometer

– Simultaneous measurement of fission cross sections and fission fragment mass and energy distributions using the RPI lead slowing down spectrometer

– Measurements of energy dependent (n,p) and (n,a) cross sections of nanogram quantities of short-lived isotopes. (collaboration with LANL).

– Capture cross section measurements• Other

– Research on medical isotope production– S(a,b) measurements (at SNS in ORNL)


Resonance Region


Transmission Experiment

Li-Glass Neutron DetectorNeutron Beam

Neutron Beam

Sample

)exp(Out Sample

In SampletN

C

CT

N – Number density [atoms/barn]t – Total cross section

Li-Glass Neutron Detector

Two Experiments:1. Sample Out

2. Sample In


Capture Experiments

Gamma RaysNeutron Beam


t

tNY

)exp(1

The capture Yield:

Sample

YCounts – neutron flux – detection efficiency


Resonance Cross Section Measurements Data Analysis

Data Reduction

Experiment

Data Analysis

CollectTransmission Data

ThermalData & Background

EpithermalData & background

Reduce toTransmission

2-5 samples

Fit DataSAMMY code

CollectCapture Data

ThermalData, Background &

Flux

EpithermalData, background &

Flux

Reduce toCapture Yield

2-5 samples

Resonaceparameters

Various Parameters

• US Cross Section Evaluation Working Group (CSEWG)

• Users - Evaluated Data Files ENDF/B-VII.1


Elemental Molybdenum

0 50 100 150 2000.0

0.2

0.4

0.6

0.8

1.0

0 50 100 150 200

0.0

0.2

0.4

0.6

0.8

1.0

0 50 100 150 200

1E-3

0.01

0.1

0.5

Tra

nsm

issi

on

200-mil Mo SAMMY calc 100-mil Mo SAMMY calc 50-mil Mo SAMMY calc 25-mil Mo SAMMY calc 10-mil Mo SAMMY calc 5-mil SAMMY calc ENDF/B-VI.8 200-mil ENDF/B-VII 200-mil

Energy, eV

Tra

nsm

issi

on

250-mil Mo SAMMY calc ENDF/B-VII.0 250-mil ENDF/B-VI.8 250-mil 100-mil Mo SAMMY calc

Cap

ture

Yie

ld

20-mil Mo SAMMY calc ENDF/B-VII.0 20-mil ENDF/B-VI.8 20-mil 10-mil Mo SAMMY calc 5-mil Mo SAMMY calc 2-mil Mo SAMMY calc


Elemental Molybdenum 120 eV - 145 eV

120 125 130 135 140 145

0.00

0.05

0.10

0.15

0.200.00

0.20

0.40

0.60

0.80

1.00

Cap

ture

Yie

ld

Energy [eV]

20-mil Mo 10-mil Mo 5-mil Mo 2-mil Mo SAMMY calc ENDF/B-VII.0 20-mil

Tra

nsm

issi

on 200-mil Mo 100-mil Mo 50-mil Mo 25-mil Mo 10-mil Mo 5-mil SAMMY Fit ENDF/B-VII 200-mil


Gd Thermal Region - Separated Isotopes

0.002 0.01 0.1 1-0.10.00.10.20.30.40.50.60.70.80.91.01.11.2

0.002 0.01 0.1 1-0.10.00.10.20.30.40.50.60.70.80.91.01.11.2

Energy [eV]

Tra

nsm

issi

on

LX-2 155Gd

LX-4b 155Gd

LX-5 157Gd

LX-7 157Gd 0.025-mm metal 0.051-mm metal SAMMY fit

Cap

ture

Yie

ld

LX-4 155Gd

LX-9 155Gd

LX-10 157Gd

LX-11 157Gd SAMMY fit

0.02 0.03 0.04 0.05-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.02 0.03 0.04 0.05-0.10.00.10.20.30.40.50.60.70.80.91.01.11.2

Cap

ture

Yie

ld

LX-9 155Gd LX-10 157Gd RPI ENDF

Energy [eV]

Tra

nsm

issi

on

LX-4b 155Gd LX-7 157Gd 0.025-mm metal RPI ENDF


235U Capture & Fission Yield Data - Epithermal Measurement

• Challenges:• Normalization• False capture due to neutron scattering

Normalize experimental fission yield to resonance

Use two equations for predominantly capture and fission resonances

Solve the two equations for k2 and k3

► Need 2 resonances with known parameters ◄

fENDFf YkY 1

86.0

fENDF YkkYkY 222 132

63.0f

fENDF YkkYkY 111 132

0.00

0.05

0.10

0.15

0.20

0.25

0.30

10 15 20 25 30 35 40 45 500.00

0.05

0.10

0.15

0.20

0.25

0.30

Yie

ld

RPI Capture Sammy Capture

Normalization

Yie

ldf

Neutron Energy [eV]

RPI Fission Sammy Fission

600 700 800 900 10000.00

0.01

0.02

0.030.00

0.01

0.02

0.03

Yie

ldf

Neutron Energy [eV]

RPI Fission Sammy Fission

Yie

ld

RPI Capture Sammy Capture

Solve for k1 @ 19.3 eV res

@ 19.3 eV res@ 11.7 eV res

63.0f


0.005

0.01

0.1

0.2

100 10000.005

0.01

0.1

0.2

Y

Capture RPI - Experiment ENDF/B-7.0 JENDL4 SAMMY ENDF7 Capture

Yf

Energy [eV]

Fission RPI - Experiment ENDF/B-7.0 JENDL4 SAMMY ENDF7 Fission

Comparing 235U Fission and Capture with Evaluations

• Fission is in excellent agreement with evaluations

• Capture data has up to 8% multiple scattering that must be taken into account during the analysis

• Capture error is about 8%

• 0.4-1 keV capture data is closer to ENDF/B-7.0

• 1-2 keV ENDF/B7.0 too high JENDL 4.0 too low.

• E>1 keV data is slightly higher than evaluations but within errors.


High Resolution Transmission Detector• Modular Li-Glass detector at 100m flight path

– Extends our capabilities to the unresolved resonance region

– Measurement of 95,96,98,100Mo completed.

Neutron Beam

6Li-Glass

100m flight station

LINAC Target Room

45m flight station


Mo Isotopes in the Resonance Region100m Flight Path

• Resonance parameters analysis in progress

• Data provide information to extend the resolved resonance region of several isotopes

0.0

0.5

1.0

0.0

0.5

1.0

0.0

0.5

1.0

1000 10000 20000 30000 40000 500000.0

0.5

1.0

Mo-98 Exp Mo-98 ENDF-7.0


Tra

nsm

issi

on



Energy [eV]


Mid-Energy Capture DetectorSystem Overview

• 4 C6D6 detector modules manufactured by EljenTechnology

• Low mass, low neutron sensitivity design

• Located at 45m flight path in newly constructed flight station

• Measurements made from 1 eV to 1 MeV

• Requires a weighting function


natFe Capture measurement• natFe was used as a test to compare with evaluations and other measurements

– The RPI data (45m flight path) has good energy resolution compared to the Spencer ORELA data (40m flight path)

– The RPI data provide information above 700 keV (next slide)

10 20 30 40 50 60 70 80 90 1000.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0.11

Spencer: N=0.0105 atm/bRPI: N=0.17133 atm/b

Cap

ture

Yie

ld

Energy [keV]

RPI (150 keV Cut) RPI/Sammy (ENDF/B-VII.1) Spencer/Sammy (ENDF/B-VII.1) Spencer 1994 (ORELA)

300 320 340 360 380 400 420 44010-6

10-5

10-4

10-3

10-2

10-1

Cap

ture

Yie

ld

Energy [keV]

RPI (150 keV gamma cut) RPI/Sammy (ENDF/B-VII.1) Spencer/Sammy (ENDF/B-VII.1) Spencer 1994 (ORELA)


natFe Capture Cross Section above 847 keV

• New capture data obtained above 847 keV and 1409 keV inelastic states in 56Fe and 54Fe

• Capture signal separated from inelastic scattering signal by post-processing digitized waveforms with different energy deposition cutoffs

• Good agreement with other experiments

• The data is lower than the evaluations above 1400 MeV 750 1000 1250 1500 1750 2000600

10-4

10-3

10-2

10-1

100

101

54Fe 1st inelastic state

RPI (150 keV Cut) RPI (900 keV Cut) RPI (1410 keV Cut) Spencer 1994 Malyshev 1964 Diven 1960 ENDF/B-VII.1 JEFF3.1

Cro

ss S

ectio

n [b

]

Energy [keV]

56Fe 1st inelastic state


Unresolved Resonance Region


New Method – Fe Filtered Beam CaptureResults for 181Ta

• Measurements performed on 181Ta using Fe-filtered beam technique

• 30cm thick Fe filter removes all beam-related gamma and neutron background

• Provides a quasi-monoenergeticneutron source corresponding to deep minima in the Fe cross section

103 104 105 106 1070.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Tra

nsm

issi

on

Energy [eV]

30cm Nat. Fe


Mid-Energy Capture DetectorExperimental Results-181Ta

• Count rates for Ta and B4C samples were summed under each filter transmission peak.

• Pb scattering sample used to confirm negligible neutron background

5.0 7.5 10.0 12.5 15.00.0

5.0x104

1.0x105

1.5x105

2.0x105

Wei

ghte

d C

ount

s

TOF [s]

6mm Ta 13mm B

4C

10mm Pb

6.8 7.0 7.2 7.4 7.6 7.8 8.0 8.2 8.40.0

5.0x104

1.0x105

1.5x105

2.0x105

Wei

ghte

d C

ount

s

TOF [s]


181Ta Iron Filtered Beam Capture Measurement:Cross Section

• As expected thick sample=problems– Self shielding correction is high

– Multiple scattering correction is high

– Need to work on better understanding of the weighting function and it validity

• Thin sample support the JEFF-3.1/3.2 evaluation

• Possible contamination from inelastic scattering apparent in ENDF/B-VII.1

10 100 1000 50000.00

0.25

0.50

0.75

1.00

1.25

1.50

1.75

2.00

181Ta (n,)

Cro

ss S

ectio

n [b

]

Energy [keV]

ENDF-B/VII.1 JEFF-3.1 JENDL-4.0 Block (1972) Lindner (1976) Macklin (1984) Yamamuro (1980) Miskel (1962) Reffo (1982) Brzosko (1969) RPI 2014 (2mm sample) RPI 2014 (6mm sample)


Fast Region


Water Cooled Ta

Target

SampleEJ-301 Liquid Scintillator

Modular Detector

250 m

CollimationCollimationCollimation

U/Pb Filter

High Energy Transmission Experimental Setup

Graphite Samples

33

137 5

Nominal thickness in cm


Beryllium Transmission

0.5 1 100.0

0.2

0.4

0.6

0.8

1.0

Be 2 cm Be 4 cm Be 8 cm ENDF/B-VII.0 JENDL3.3

Tra

nsm

issi

on

Energy [eV]

15

234

8

Beryllium samplesSample thickness is given in cm

Reconfigured the detector with two units to reduce background


Beryllium Total Cross Section (Low Energy)

0.4 0.5 0.6 0.7 0.8 0.9 1.03

4

5

6

7

8

2 cm sample 4 cm sample Filtered Beam experiment ENDF/B-VI.8 ENDF/B-VII.0 JENDEL 3.2

Cro

ss S

ectio

n [b

arn]

Energy [MeV]

M.J. Rapp, Y. Danon, F.J. Saglime, R.M. Bahran and D.G. Williams, G. Leinweber, D.P. Barry and R.C. Block, “Beryllium and Graphite

Neutron Total Cross Section Measurements from 0.4 to 20 MeV”, Nuclear Science and Engineering, Vol. 172, No. 3. Pages 268-277, November 2012 (2012).


Ti Total Cross Section Measurements0.5 – 20 MeV

• 250m flight path measurement shows structure that was not resolved in prior measurements

• JEFF 3.1.2 shows an energy shift

• ENDF/B-VII.1 lower resolution than JEFF 3.1.2 and ENDF/B-VII.0

0.5 1 10 200

1

2

3

4

5

6

7

8

9

t [b

]

Energy [MeV]

8cm Ti data 12cm Ti data ENDF/B-VII.1

0.60 0.65 0.70 0.75 0.800

2

4

6

8

10

t [b

]

Energy [MeV]

250m RPI data 100m RPI data Schwartz et. al. (1974) ENDF/B-VII.0 ENDF/B-VII.1 JEFF 3.1.2

12 cm8 cm


Zr Total Cross Section Measurements (0.5-20 MeV)

• 100m flight path• Used low Hf (less than 100 ppm) Zr metal• ENDF/B 6.8 seems like a better fit for E<16 MeV• New partially resolved structure below 2.0 MeV• Data can be used to improve the unresolved resonance region evaluation

0.5 1.0 1.5 2.0 2.5 3.03

4

5

6

7

8

9

10

11

12

t [b

arn]

Energy [MeV]

RPI Experiment Arpil - May 2008

ENDF/B-6.8

ENDF/B-7.0

JEFF 3.1

JENDL 3.3

2 4 6 8 10 12 14 16 18 203.0

3.5

4.0

4.5

5.0

5.5

t [

barn

]Energy [MeV]

RPI Experiment Arpil - May 2008

ENDF/B-6.8

ENDF/B-7.0

JEFF 3.1

JENDL 3.3


Fast Neutron Scattering

Quasi-differential neutron scattering and angular distributions.


TOF Scattering Measurement• Measure TOF: t = t1 + t2; where t1 » t2

• All scattering events: E2 < E1

• For elastic scattering with A » 1: E1 ~ E2

• Assuming L = L1 + L2 than total TOF, t, can be used to calculate the incident neutron energy, E1(t)

L1, t1, E1

L2, t2, E2L1 ~ 30m

L2 ~ 0.5m

1

1

1)(

2

21

tc

LcmtE n


238U Scattering Measurement - JEFF 3.2

Library FOM

JEFF-3.1 3.0

JEFF-3.2 2.8

Library FOM

JEFF-3.1 20.4

JEFF-3.2 7.9

500 800 1200 1600 2000 2400 2800 31280

1000

2000

3000

4000

50000.10.51251020

153 deg

Energy [MeV]

Cou

nts

Time of Flight [ns]

Uranium Data JEFF-3.2 JEFF-3.1

500 800 1200 1600 2000 2400 2800 31280

1000

2000

3000

4000

5000

6000

7000

80000.10.51251020

60 deg

Energy [MeV]

Cou

nts

Time of Flight [ns]

Uranium Data JEFF-3.2 JEFF-3.1

Significant improvement in JEFF3.2


Fe Scattering Measurement - Setup

The neutron beam size is smaller than the sample.

EJ-301 Liquid Scintillator Neutron Detectors

• Fe Sample• Dimensions 77.0 x

152.6 x 32.2 mm

Evacuated Flight Tube


natFe Scattering - 61°

Library FOM

ENDF/B-VII.1 9.5

JEFF-3.2 9.5

JENDL-4.0 8.4

Reference FOM

Graphite 1.3

1000 1500 2000 2500 30005000

500

1000

1500

2000

2500

30000.511.5251020

61 deg

Energy [MeV]

Cou

nts

Time of Flight [ns]

NatFe Data ENDF/B-VII.1 JEFF-3.2 JENDL-4.0

1750 2000 2250 2500 2750 300015000

500

1000

1500

2000

2500

30000.511.52

61 deg

Energy [MeV]

Cou

nts

Time of Flight [ns]


800 1200 1600 2000 2400 2800500 31280

500

1000

1500

2000

2500

30000.511.5251020

Energy [MeV]

Cou

nts

Time of Flight [ns]

Graphite Data MCNP Results

61 deg


natFe Scattering - 153°

Library FOM

ENDF/B-VII.1 25.9

JEFF-3.2 39.8

JENDL-4.0 23.4

Reference FOM

Graphite 4.9

1800 2100 2400 2700 30001550 31280

1000

2000

3000

4000

5000

6000

7000

8000

9000

100000.512

153 deg

Energy [MeV]

Cou

nts

Time of Flight [ns]


800 1200 1600 2000 2400 2800500 31280

2000

4000

6000

8000

100000.51251020

Energy [MeV]

Cou

nts

Time of Flight [ns]

Graphite Data MCNP Results

153 deg

1000 1500 2000 2500 30005000

1000

2000

3000

4000

5000

6000

7000

8000

9000

100000.51251020

153 deg

Energy [MeV]

Cou

nts

Time of Flight [ns]



Inelastic to Elastic Ratio

• Multiple scattering effects included in MCNP simulations• Statistical and systematic uncertainties included in analysis

1.4 1.6 1.8 2.00.0

0.2

0.4

0.6

0.8

1.0 Inelastic to Elastic Ratio JEFF-3.1

Inelastic to Elastic Ratio ENDF/B-VII.1

Inelastic to Elastic Ratio JENDL-4.0Nat

Fe Ratio

Inel

astic

-to-

Ela

stic

Rat

ioIncident Neutron Energy [MeV]

Detector 3 at 153o

1.4 1.6 1.8 2.00.0

0.2

0.4

0.6

0.8

1.0

1.2I/E Ratio JEFF-3.2I/E Ratio ENDF/B-VII.1I/E Ratio JENDL-4.0NatFe Ratio

I/E

Rat

io

Incident Neutron Energy [MeV]

Detector 6 at 130o

1600 1650 1700 1750 1800 1850 190015500

1000

2000

3000

4000

5000

6000

7000

8000

9000

1000011.41.51.61.71.81.92

153 deg

Energy [MeV]

Cou

nts

Time of Flight [ns]


1600 1650 1700 1750 1800 1850 19001550 19250

500

1000

1500

2000

2500

3000

350011.41.51.61.71.81.92

130 deg

Energy [MeV]

Cou

nts

Time of Flight [ns]



Comparing Experiments and SimulationElastic scattering

• Experimental elastic scattering was inferred from 0.5 to 2.0 MeV– The experimental data is reasonably represented by a simulation with ENDF/B-VII.1

• Collaborating with ORNL to improve new 56Fe evaluation

1500 1800 2100 24000

500

1000

1500

2000

2500

3000

35000.10.50.851251020

130 deg

Energy [MeV]

Cou

nts

Time of Flight [ns]

Total Scattering Data ENDF/B-VII.1 Total

Elastic Scattering Data ENDF/B-VII.1 Elastic

1500 1800 2100 24000

1000

2000

3000

4000

50000.10.50.851251020

153 deg

Energy [MeV]

Cou

nts

Time of Flight [ns]

Total Scattering Data ENDF/B-VII.1 Total Elastic Scattering Data ENDF/B-VII.1 Elastic


Resonance Scattering

Example of an experiment for testing the physics models of Monte Carlo codes


Resonance Scattering Experiment• Motivation – Provide a benchmark to the model developed by Dagan et al.

– Poor approximation of the scattering kernel when the cross section is energy dependent.

• Use the Time-Of-Flight (TOF) method– The TOF will correspond to the scattered neutron energy– Scattering in forward and backward scattering angles can be measured

Electron Beam

NeutronProducing Target

238U sample

Good CollimationNeutron Detector

~25.5 m

n

q


Resonance Scattering- Experimental Setup

SampleBlank

Ta Targete- beam line

Moderator


Resonance Scattering-Measured Data• Thick Sample time-of flight spectrum forwards scattering

100 200 300 400 500 600 700 800 900 1000

200

400

600

800

1000

1200

1400

1600

1800

2000

280 290 300 310 320 330 3400

200

400

600

800

1000

6.671 eV

20.972 eV

Cou

nts

TOF [s]

238U Thick sample Background (no sample)

36.68 eV

TOF [s]

Cou

nts


34 35 36 37 38 39 400

100

200

300

400

500

RPI Experiment MCNP (Modified) MCNP+S(a,b)

Cou

nts

Scattered Neutron Energy [eV]

E0=36.68 eV

Sample thickness=1/16"

34 35 36 37 38 39 400

100

200

300

400

RPI Experiment MCNP (Modified) MCNP+S (a,b)

Cou

nts


E0=36.68 eV

Sample thickness ~1/16"

34 35 36 37 38 39 400

100

200

300

400

500

RPI Experiment MCNP (unchanged) MCNP (modified) MCNP+S(a,b)

Cou

nts


E0=36.68 eV


Resonance Scattering - Results for238U Scattering

Back Forward

ThickSample

ThinSample

Back Forward

34 35 36 37 38 39 400

200

400

600

800

1000


RPI Experiment MCNP (Unchanged) MCNP (Modified) MCNP+S(a,b) Geant 4

Cou

nts


E0=36.68 eV

In 2009 all MC codes had this problem Today some still do


Lead Slowing Down Spectrometer


VacuumTi Window

ElectronBeam

He Filled Drift Section

Neutron Source(He cooled Ta Target)

LEAD

Crossed I beam + Li2Co3

180 cm

180

cm

Fission Chamber

Flux Monitor

Flux Monitor

Flux Monitor

• Tantalum target in the center produces neutrons.

• Neutrons scatter elastically with the Pb.

• Neutrons can pass through the same position several times.

• About 103-104

times higher flux than an equivalent flight path TOF experiment (5.6m).

(60 cm from corner)

Lead Slowing-down Spectrometer at RPI

67 tons of Pb


Fission Fragment Kinematics

• Objectives– Simultaneous measurement of the fission cross section

and fission fragment mass and energy distributions of small samples (~nanograms).

• Method– Use the RPI lead slowing down spectrometer and a

double gridded fission chamber.

– Samples are deposited on very thin backing (~250 nm)


SETUP

VacuumTi Window

ElectronBeam

He Filled Drift Section

Neutron Source(He cooled Ta Target)

LEAD

Crossed I beam + Li2Co3

180 cm

180

cm

Fission Chamber

Flux Monitor

Flux Monitor

Flux Monitor

Anode

Anode

Cathode

Sample

CH4 Inlet

Filter

FilterTeflon rods

q

e- e

- e- e

-

+ +

+ +

Grid

Grid

DGGV486

CFDV812

AmplifierN568B

FIFON401

FIFO

FIFO

FIFO

FIFO

FIFO

FIFO

CFD1

CFD2

CFD3

DGG1

ADCV785

TDCV775

ScalerV830

Start

Stop1

Stop2

DGG2

DGG3

Reset/Start

TRG

LINAC Pretrigger

10 MHzClock

IN1

ADC1

ADC6

ADC5

ADC4

Gate

ADC3

ADC2

Preamplifiers

VMEMM

Fission Chamber

Cathode

Anode-1

Anode-2

Grid-1

Grid-1

-3.0 KV

-1.5KV

-1.5 KV

Double Gridded Fission Chamber

Multiparameter DAQ

Collaboration with LANL• Fission cross sections.• (n,a), (n,p) measurements on small samples.


Results – Fission Fragment Mass distribution En<0.1 eV235U 239Pu

80 100 120 140 160 1800.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09252Cf Preneutron Emission Mass

Yie

ld

Mass [amu]

Hambsch Current Data

60 80 100 120 140 160 1800.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09252Cf Postneutron Emission Masses

Yie

ld

Mass [amu]

Current Data JEFF3.1

252Cf

60 80 100 120 140 160 1800.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

235U Preneutron Emission Fission Fragment Mass

Yie

ld

Mass [amu]

Hambsch Data Current Data

60 80 100 120 140 160 1800.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

Yie

ld

Mass [amu]

Current Data JEFF3.1

235U Post Neutron Emission Masses

60 80 100 120 140 160 1800.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09239Pu Post Neutron Emission Masses

Yie

ldMass [amu]

ENDF/B-VII.0 Current Data

60 80 100 120 140 160 1800.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09239Pu Preneutron Emission Masses

Yie

ld

Mass [amu]

Current Data Hambsch Data


Results – Fission Fragment Energy Distribution En<0.1 eV

40 60 80 100 120 40 60 80 100 12040 60 80 100 1200.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

Yie

ld

Energy [MeV]

252Cf Energy

235U Energy

239Pu Energy Hambsh Data


Fission symmetry in resonance clusters

10-1 100 101 102 103 104100

101

102

103

Current Data ENDF/B-VII.0

thermal 1<0.1 eV

res9res8

res7

res6

res5

res4

res3

res2

high res

f [b

arn]

Energy [eV]

0 1 2 3 4 5 6 7 8 9 10 11-0.5

0.0

0.5

1.0

1.5

2.0

2.5Symetric Fission in Resonances Relative to Thermal

Sym

reso

nanc

e/Sym

ther

mal

Resonance Number

Current Data Hambsch Data Faler Data


239Pu - Results

E<0.1 eV (region 1)

80 100 120 140 160150

160

170

180

190

200

210

Mass [amu]

TK

E [M

eV]

0.00

0.02

0.04

0.06

0.00

0.02

0.04

0.06

0.00

0.02

0.04

0.06

60 80 100 120 140 1600.00

0.02

0.04

0.06

60 80 100 120 140 160

0.00

0.02

0.04

0.06

Region 2

Region 3

Region 4

Yie

ld (

1/am

u)

Region 5

Region 6

Yie

ld (

1/am

u)

Region 7

Mass (amu)

Yie

ld (

1/am

u)

Mass (amu)

Region 9

Region 10high energy

Yie

ld (

1/am

u)

Yie

ld (

1/am

u)

Region 1 Thermal

Region 8

10-1 100 101 102 103100

101

102

103

104

1

1098

756

43

f [

barn

]

Neutron Energy [eV]

2


(n,a) cross section measurementsCompensated PIPS Detector

PIPSDet.

PIPSDet.

BNC Model 555

Ch A

Ch B

Ch D

Ch C

Ext

5M

5M

T0 fromControlRoom

45ns Cramtemodel 110

Pre-Amplifier

100ns Cremat model200 Shaper Amplifier

PhillipsScientific

Model #460Inverting

Transformer(Modifier)

PhillipsScientific

Model #460Inverting

Transformer

4.7nF 4.7nF

4.7nF4.7nF

4.7nF 4.7nF

4.7nF

4.7nF

Tabor Model8024 Function

Generator

Out

Trig In

NHQ 204MHVPS (20V)

Acqiris DC440DigitizerC

h 1

Ch 2

I/O A

I/O B

•Gamma discrimination by recording the gamma spectra on two face to face detectors

•Digital DAQ collects a bipolar signal

•Correct for background by subtracting the bare detector signal from the sample detector on an event by event basis

Sample

Sample Position


(n,a) and (n,p) measurement results• Measurement of (n,a) cross section of 147,149Sm• Demonstrate the ability to measure micro barn cross sections with the

LSDS

J.T. Thompson, T. Kelley, E. Blain, R.C. Haight, J.M. O'Donnell, Y. Danon, “Measurement of (n,α) reactions on 147Sm and 149Sm using a lead slowing-down spectrometer”, Nuc. Inst. and Meth. A, Vol. 673, pp. 16-21, May (2012)


Capture measurements with the LSDS

• Use a Lead Slowing Down Spectrometer to measure the capture rate of samples of small mass or small cross section– Detect from capture

• Criteria for a detector– Low n-capture cross section– Low n-scattering cross section– High γ detection efficiency– Small detector (reduce background)– Fast recovery from gamma flash

Sample

n from Pb

from Pb

Scattered neutron


Ta capture rate• 2mm YAP Detector, 10 Mil Ta Sample

– The measurement extends to ~50 keV– Good agreement with the simulations– Data collection time was about 20 minutes

100 101 102 103 10410-1 5x104

103

104

105

106

102

107

Cou

nt R

ate

[Cou

nts/

seco

nd]

Energy [eV]

Measurement ,10 Mil Ta, 1 YAP Detector MCNP ENDF/B-II.1 10 Mil Ta, 1 YAP Detector


100 101 102 103102

103

104

105

106

107

Rat

e [c

ps]

Time [s]

Experiment, 2mm YAP 3mm Nickel Sample Background Sample - Background

Ni Capture rate• 2mm YAP detector, 3mm nickel sample

– Low capture cross section Low S/B– Reasonable agreement with ENDF/B-VII.1 – Additional peaks observed near 200-300 eV possible impurities in sample

10-1 100 101 102 103 104 5x104102

103

104

105

106

Rat

e [c

ps]

Energy [eV]

3mm Nickel Sample Measurement Simulation, ENDF/B-VII.0


Prompt Fission Neutron Spectra


Experimental Setup

SamplePosition

EJ-301Detectors

GammaDetectors

EJ-204Detector ＊

E1

L1=30 m

E2

L2=0.5m

4 Gamma Detectors(top view)

Neutron Detectors

Sample

• Neutron Detectors– EJ-204 Plastic Scintillator

• 0.5” x 5”

• 47 cm away from center of sample– 2 EJ-301 Liquid Scintillators

• 3” x 5”

• 50 cm away from center of sample

• Gamma Detectors– 4 BaF2 detectors on loan from ORNL– Hexagonal detectors 2” x 5”

– 10 cm from center of sample– ¼” lead shield between detectors

• Reducing scattering between detectors

energyneutronfission E

energyneutron incident E

distanceflightpath

3.72

2

1

2,1

2/1

2

2

1

1

Lm

eVsk

E

kL

E

kLToF


252Cf Prompt Fission Neutron Spectrum• Good agreement seen between the RPI datasets in the overlap region

from 0.7 MeV to 2 MeV

• Combined datasets provide measurement from 0.05 Mev to 7 MeV


238U Prompt Fission Neutron Spectrum

• Spectrum is integrated over two incident energy regions, first chance fission and second chance fission

• Data shows good agreement with current evaluations• Increase near 1 MeV agrees with new data by Sardet et. al.• Both spectra normalized at 2.25 MeV


LINAC 2020 Refurbishment and Upgrade Plan

• Project aims at refurbishment and upgrade of the accelerator– Increase neutron production as short pulses

• Increase the electron beam energy

• Modernize the electron beam control system

– Provide longevity• Replace all major components and acquire spares

• Funded by DOE-NR and NCSP through BMPC/KAPL

Documents

Experimental Capabilities for Applied Nuclear …bang.berkeley.edu/wp-content/uploads/DANON_LBNL_2015.compressed-1.pdfExperimental Capabilities for Applied Nuclear Science at RPI