Neutron Cross-Section Measurements from ORELA

K.H. Guber, Oak Ridge National Laboratory,

Oak Ridge, TN, USA

50 51 5 2 53 54 55 56 57 58 59 60

0 .000

0 .025

0 .050

0 .075

0 .100

ORELA d ata

σ(n,

γ) (b

)

En ergy (keV )

ORELAORELA

Applications

Computational modeling

Basic Science

Evaluated Nuclear Data Files (ENDF/B)

AMPXAMPX

SAMMYSAMMYCross-SectionEvaluations

ORNL Data ORNL Data Support for Nuclear Support for Nuclear

ApplicationsApplications

Nuclear Astrophysics

OakRidgeElectronLinearAccelerator

• High intensity, pulsed neutron, positron and γ-ray source

• Four section, L-band electron linear accelerator, Peak current: 40 amps, Electron energy: 180 MeV , Rep. rate: 1 -1000 Hz, Pulse width: 2 - 30 nsec, Power on target: 60 kW maximum

• Neutron production: 1014 n/sec, 1011 n/pulse, Positron production: 108 e+/sec

• Facility capabilities: simultaneous experiments at different flight -paths (10), -stations (18), and -lengths (9-200m, underground).

e--Gun

Klystron

OakRidgeElectronLinearAccelerator• High flux (1014 n/sec) => gram-

sized, affordable samples• Excellent resolution (∆t=2-30 ns)

=> good S/N facilitates better evaluations

• “White” neutron spectrum from En ~ 0.01 eV - 80 MeV => reduces systematic uncertainties

• Measurement systems and backgrounds well understood =>very accurate data

• Simultaneous measurements => (n,γ), (n,α), (n,n′), (n,f), and σtotal experiments at the same time on different beam lines

• Measurements on over 180 Isotopes:ORELA measurements have contributed to ~80% of U.S. Evaluated Nuclear Data File (ENDF/B) evaluations

(n,γ)

Neutron Scattering @200m

Transmission 18,80,200m

(n,γ)

(n,α)

10-3 10-2 10-1 100 101 102 103 104 105 106 107 108105

106

107

108

109

1010

1011

ORE

LA F

lux

n/se

c/sr

/kW

Cap

abili

ties

Neutron Energy (eV)

Transmission18m Flight Path Ta+Poly

80m, 200m Flight Path,Ta or Be Target

Capture40m Flight Path, FP7 and FP6

Fission18m Flight Path Ta+Poly

80m, 200m Flight Path,Ta or Be Target

Scattering 200m Flight Path, Ta or Be Target

9 m Flight Path(n,α),(n,p)

Opportunities

Inelastic scattering

4πBaF2, (n,γ),α, γ-ray -multiplicity and -production

Experiment Requirements

• Duration: ~ weekR = nσφε + Rbkg.

Maximize n, φ, and ε, minimize Rbkg.

Except: minimize n because samples can be expensive (enriched isotopes) and radioactive samples contribute to background. Increasing ε may lead to worse background. Increasing φ may lead to counting-rate problems.

Minimize Rbkg, especially sample-dependent part.Measure as much as possible (e.g. σt, standards).

Experimental TechniquesType White Source Monoenergetic

Facilities Van de Graaff, Electron and Proton Linacs, Lead Slowing-Down Spectrometer

Van de Graaff, Reactor, Electron Linac

Pros All energies at once.Wide energy range.Moderate to high flux.Excellent to modest resolution.Simultaneous experiments.More information (e.g. resonance parameters).

High flux.Simpler experiments.Activation and quasi-Maxwellian spectrum possible.

Cons Backgrounds may be more troublesome: γ-flash, neutron sensitivity and other sample-dependent backgrounds.More complicated analysis.

Only one energy and one experiment at a time.Poor or no resolution.

Neutron Capture and Total Cross Section Experiments at a White Neutron Source:

• Time-of-flight technique used to determine incident neutron energy.“Clocks” used have typically 1nsec resolution.

•Pulsed electron beam starts clock. γ-ray or neutron detector stops clock.

vn = L/t

En = mnv2/2

• Filters used to reduce frame-overlap background from low-energy neutrons and to reduce γ-flash effects.

Ele

ctr

on

B

Neutron ProductionTarget Collimator

Ne

utr

on

s

Filters

Deuterated BenzeneDetectors

40 m

Sample

Capture Setup at ORELA

Ele

ctr

on

Neutron ProductionTarget Collimator Detector

9 m80 m

Ne

utr

on

s

Sample

Blank

Filters

Li-glass6T.O.F. T.O.F.

Transmission Setup at ORELA

FacilityParameters

United States Europe

ORELA LANSCE IPNS RPI GELINA n_TOFSource e- linac p spallation p spallation e- linac e- linac p spallation

Particle E (MeV)

140 800 450 >60 120 20000

Flight Path (m) 10-200 7-55 ~6-20 10-250 8-400 185

Pulse Width (ns)

2-30 125 70-80 15-5000 1-2000 7

Max Power (kW)

50 64 6.3 >10 11 45

Rep Rate (Hz) 1-1000 20 30 1-500 Up to 900 0.278-0.42

Best Intrinsic Resolution (ns/m)

0.01 3.9 3.5 0.06 0.0025 0.034

Neutrons/s 1 × 1014 7.5 × 1015 8.1 × 1014 4 × 1013 3.2 × 1013 8.1 × 1014

Cross-Section Measurement Facilities

Facilities Comparison for 20m Flight path

ORELA GELINA LANSCE IPNS n_TOFHypothetical Flight path length

[m] 20 20 20 20 20

Pulse width [ns] 24 1 125 80 7

Power [kW] 50 11 64 6.3 45

Repetition Rate [Hz] 1000 800 20 30 0.42Neutron Flux @ 1keV [neutron/s/cm2/eV] 2.50E+01 1.00E+01 1.20E+02 1.00E+02 2.50E+02

Neutron Flux @ 1keV [neutron/s/cm2] 2.50E+04 1.00E+04 1.20E+05 1.00E+05 2.50E+05

Intrinsic Resolution [ns/m] 1.2 0.05 6.25 4 0.35Realistic Resolution dE@ 1keV

[eV] 0.97 0.98 3.48 2.25 4.49FOM @ 1keV (Flux/(dE/E)^2)

[n/s/cm2] 2.67E+10 2.60E+10 9.93E+09 1.97E+10 1.24E+10

Neutron Cross-Section Measurements In The Resolved Resonance Range

•Neutron flux is important but alone cannot guarantee accurate measurements.

•Neutron Energy resolution is important.• Goal to resolve many resonances in order to obtain reliable average resonance parameters. These are important to perform the analysis of the unresolved energy range and statistical model calculations.

• Resolved resonances help to identify and disentangle isotopic impurities in the sample.

• Resolved resonances help to apply individual and no average correction to the data (self-shielding, multiple-scattering).

Neutron Cross-Section Measurements

1 0 0 0 1 2 0 0 1 4 0 0 1 6 0 0 1 8 0 0 2 0 0 00

2 0

4 0

6 0

8 0

1 0 0

1 2 0

(n,γ)

cro

ss s

ectio

n [b

]

N e u t r o n E n e r g y [ e V ]

Au(n,γ) LANSCE 8m

Au(n,γ) ORELA 40m

1.10 1.12 1.14 1.16 1.18 1.20 1.22 1.24 1.26 1.28 1.30

0

10

20

30

40

σ(n,

γ) [b

]

Neutron Energy [keV]

ORELA Data SAMMY Fit

192

192

192

192

192

192

192

1 0 0 1 0 0 0 1 0 0 0 00 .0 1

0 .1

1

1 0

σ(n,

γ)[b

]

E n e r g y [e V ]

Resolved resonances help to apply individual and no average correction to the data (self-shielding, multiple-scattering).

Multiple scattering

High resolution data help to identify and disentangle isotopic impurities. Example: 192Pt, one of the rarest isotopes in the world, only 700mg with 57% enrichment.

• Flight path length, the longer the better.• Pulse width of the neutron burst, the shorter the better:

• Typically fixed with spallation sources (tens of ns to hundreds of ns)• Linac sources can vary pulse width ( 1ns up to tens of ns).

• Source moderation distance• The uncertainty of the creation location of the neutron inside the target/moderator has to be taken into account for the resolutionfunction.

• ORELA is an undermoderated source with relatively small neutron production target. Spallation sources are usually optimized for thermal neutron flux, this requires large moderators.• The moderation effect put tails on resonances due to delayed

neutrons.• Hinders resolution of closely spaced resonances.• Produces background in unresolved energy range which cannot be

corrected. This effect is of the order of 16% for 20 keV (Cocevaet al. 2002) for n_TOF and can not be estimated quantitatively.

Neutron Energy Resolution

Beryllium housing

Target Configuration ORELA

Neutron Production GELINA

NEUTRONMODERATOR

ELECTRONBEAMLINE EXIT

NEUTRONTARGET

NEUTRONFLIGHT PATHS

• e- accelerated to Ee-,max ≈140 MeV

• (e-, γ) Bremsstrahlung in U-target (rotating & Hg-cooled)

• ( γ , n) , ( γ , f ) in U-target

• Low energy neutrons by water moderator in Be-canning

Neutron Production GELINA

Average Current : 75 µAAverage Electron Energy : 100 MeVPulse Width : 1nsFrequency : 40 – 800 Hz

10-2 100 102 104 106102

103

104

105 GELINA 30 m 800 Hz

Exp. Mod. Fast

MCNP Mod. Fast

dϕn/d

lnE

n / (

cm-2 s

-1)

Neutron Energy / eV

SHIELDING MODERATED SPECTRUM

SHIELDING FAST SPECTRUM

PhD M. Flaska

Neutron Target n_TOF

Old Pb block 80cm

Neutron Energy Resolution

4 0 5 0 6 0 7 0 8 0

0

2 0

4 0

6 0

8 0

1 0 0 4 0 5 0 6 0 7 0 8 00 . 1

1

1 0

1 0 0

1 0 0 0

1 0 0 0 0

(n,γ)

cro

ss s

ectio

n [b

]

N e u t r o n E n e r g y [ e V ]

Au(n,γ) ORELA 40m

Au(n,γ) LANSCE 8m Au(n,γ) n_TOF CERN 185m

3.0 3.5 4.0 4.5En (keV)

-1000

4000

9000

14000

σ (m

b)

ORELA 40m flight path

FZK 1m flight path

Superior Resolution at ORELA Results in Much Better S/N

•Measured using BaF2ball at FZK.

•Measured using C6D6 at ORELA.

Moderation Distance Distribution• The uncertainty of the creation

location of the neutron inside the moderator has to be taken into account for the resolution function.

• This can be quite sizeable for large target and moderator assemblies.

• The effect is that it will put tail on the resonances in the resolved neutron energy region.

• Additionally it will produce a back-ground in the unresolved region which can not be corrected for.

• This effect is of the order of 16% for 20 keV (Coceva et al. 2002) for n_TOF and can not be estimated quantitatively.

-5 0 5 10 1510-4

10-3

10-2

10-1

100 En = 10000 - 30000 eV

Distance / cm-5 0 5 10 15

10-4

10-3

10-2

10-1

100 MCNP (PhD M. Flaska) Coceva

En = 100 - 1000 eV

Distance / cm-5 0 5 10 15

10-4

10-3

10-2

10-1

100 En = 1 - 10 eV

Res

pons

e /

(1/c

m)

Distance / cm

GELINA

ORELA

n_TOF

Average Moderation Distance

0.1

1

10

100

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

Neutron Energy (eV)

∆L

(cm

)

ORELAn_TOF

• Due to moderation the neutron flight path is energy dependent.

• n_TOF [cm]:

• ORELA [mm]:

EL ⋅=∆ 101.0

2)(ln283.0ln6.11.22 EEL ⋅+⋅−=∆

LLEL ∆+= 0)(

3 0 0 4 0 0 5 0 0 6 0 0E n ( k e V )

σ (b

)

1 0 - 5

1 0 - 4

1 0 - 3

1 0 - 2n _ T O FO R L E AL u j a n

M g 2 5 C o m p 3 0 0 t 6 0 0 A u g . 2 , 2 0 0 6 1 2 : 2 2 : 3 0 P M

2 5 M g ( n , γ )

The Influence of Resolution

3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0E n e r g y ( e V )

0

1 0 0

2 0 0

3 0 0

4 0 0

5 0 0

6 0 0

Tota

l Cro

ss S

ectio

n (b

)

O R E L A U 2 3 3 T o t a l a t T = 1 0 KP a t t e n d e n e t a l . 1 9 6 3

SAMMY Calculations

Measured Data

n-TOF (180 m) <-> GELINA (60 m)

3.30 3.35 3.400

2

4

Cou

nts/

(1/n

s) [a

rb. u

nits

]

206Pb(n,γ) En = 3.36 keV

Neutron Energy / keV

GELINA 60 m n-TOF 200 m

33.6 34.0 34.4 34.80.000

0.005

0.010

0.01556Fe(n,γ) En = 34.21 keV

GELINA 60 m n-TOF RPI (32 - 40 keV)

Cap

ture

Yie

ld [a

rb. u

nits

]

Neutron Energy / keV

P. Schillebeeckx, IRMM

Doppler - Resolution Broadening @20 m for 241Pu

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05

Energy (eV)

Wid

th/R

esol

utio

n

Doppler 300KDoppler 70KAvLSpacingIPNS Experiment 20m, 80nsLANSCE 20m, 125nsORELA 20m 8nsORELA 80m 8ns

Trouble with Weighting Functions• 20% discrepancy found in neutron

width of 1.15-keV resonance in Fe measured with C6D6 compared to transmission measurements.Fe cascade is hard while those for Au and Ag are soft.

• Corvi et al. (1988) showed that measured weighting functions could solve discrepancy.

• Perey et al. (1988) showed that EGS simulations agreed with 207Pb(n,γ) cascades and that EGS-4 weighting functions also solved Fe discrepancy. Sample and surrounding material was neglected in previous weighting function calculations.

Results for 56Fe with Weighting Functions for C6D6 Detectors

Exp. Type Lab Year Det.Type WeightF. gΓnΓγ/Γ[meV]

Γn[meV]

Capture Geel 1991 C6D6 Experim. 56.7 1.9 62.9 2.1Capture Harwell 1988 C6D6 EGS4 59.5 3.0 66.4 3.3Capture Oak Ridge 1988 C6F6 EGS4 58.0 2.9 64.5 3.0Capture Oak Ridge 1988 C6D6 EGS4 56.8 2.3 63.0 2.5Capture Oak Ridge 1994 C6D6 EGS4 55.8 1.7 61.8 1.9Trans-mission

Oak Ridge 1985 55.7 0.8 61.7 0.9

± ±

± ±± ±± ±± ±± ±

Much of the Old Neutron Data (on Which Current Evaluations Are Based) Are Seriously Incorrect

• Some problems with the old data:– Underestimated neutron

sensitivity correction – Low-energy cut off of 3 keV– No high energy (>100 keV)

data– Incorrect weighting function– Poor resolution– Poorly characterized samples,

i.e. water in the sampleEx: Large neutron sensitivity of older measurements led to many erroneously-large resonance areas in current evaluations.

30 40 50 60

0.00

0.05

0.10

0.15

(n,γ)

[b]

Neutron Energy [keV]

ORELA Si Capture ENDF/B-VI

Modified capture data measurement system has significantly less structure

Detector housingremoved

Aluminum guidereplaced by C-fiber tube

Sample changerreplaced

C6F6 Scintillator replaced

New ORELA Weighting Functions Demonstrated to be Accurate to Better Than 3%

Excellent agreement between ORELA C6D6 (Koehler et al.) and FZK BaF2 (Voss et al.) 134,136Ba(n,γ) measurements.

Hardness of cascade varies considerably from resonance-to-resonance, but no systematic difference between capture kernels observed.

Excellent (<3%) agreement for average cross sections.

1022 3 4 5 6 7 8 2 3 4

En (keV)

0

50

100

150

200

250

σ (m

b)

Koehler et al.Voss et al.Koehler et al.Voss et al.

}}

134Ba(n,γ)

136Ba(n,γ)

2 4 6 8 10 12 14 16 18 20En (keV)

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Koe

hler

et a

l./Vo

ss e

t al.

Ratio of Capture Kernels for 136Ba

New 95Mo(n,γ) experiments

•AGB stellar models over predict the abundance of 95Mo compared to observation in SiC grain which origin from an AGB star where the s-process takes place.

•M. Lugaro et. al. 2003: calculations show a 30% enhancement in the (n,γ) cross section for 95Mo would solve the problem.

New 95Mo(n,γ) and σT Measurements at the Oak Ridge Electron Linear Accelerator (ORELA)• 95Mo(n,γ) measured using new apparatus on F.P. 6 at 40 m.C6D6 using PHWT.6Li-glass flux monitor.Separate background measurements.Modified to measure coincidence PH data.

• 95Mo σt measured on F.P. 1 at 80 m.6Li-glass detector.Separate sample-out, CH2, and Bi measurements.Transmission.

Capture of Incident Neutrons Detector at ORELA

“CINDORELA”

New 95Mo(n,γ) and σtData from ORELA

Resonance analysis using SAMMY.318 resonances to 10 keV.Only 106 previously known.Only 32 previous firm Jπ

assignments.

• Transmission data yield parity of resonance if neutron width is large enough.

En (keV)0.60 0.65 0.70 0.75 0.80

0

20

40

0.0

0.5

1.0

Tran

smis

sion

3.70 3.75 3.80 3.85 3.90

0

10

σ (b

)0.0

0.5

1.0

DataSAMMY

4.65 4.70 4.75 4.80 4.85 4.90

0

5

0.0

0.5

1.0

6.50 6.55 6.60 6.65 6.70

024

0.0

0.5

1.0

95Mo+n

Transmission = exp(-nσt)

s s s s

s s s

s s s

s s

p p

p

p p pp

The Importance of Total Cross Section Data

• More complete resonance parameter data will help improve nuclear statistical model.

• Is indispensable for obtaining the most accurate (n,γ) reaction rates. See resonances not visible in (n,γ) data. Improved self-shielding and multiple scattering corrections.

• Lack of good total cross section data can lead to serious errors in these corrections and hence in the cross sections.

1014 5 6 7 8 9 2

En (keV)

350

450

550

650

750

850

σγE

1/2

(mb

keV1

/2)

Koehler et al., Num. Int.Koehler et al., ResonanceWisshak et al., Num. Int.Wisshak et al., Resonance

116Sn(n,γ)

•Ex: 116Sn Use of incorrect neutron widths led to incorrect low-energy cross sections (Wisshak et al.).

The Importance of Total Cross Section Data• No high-quality σt data available previously. Needed for

accurate determination of reaction rate from resonance region because measurements made with thick samples.

• Compare results from pulse-height weighting technique to results from 4π BaF2 detector.

19750 19760 19770 19780 19790 19800 19810 19820E n (eV)

0

1

2

3

4

5

6

7

8

9

σγ (b

)

136 Ba(n, γ ) Calculated by SAMMY

Present WorkΓ γ = 248 meVΓ n = 3660 meVA γ = 465 meV

Voss et al.Γ γ = 269 meVΓ n = 502 meVA γ = 351 meV

Resonance Self-Shielding Correction

"True""Measured"

thin <--> thick transmission Determination of statistical factor g

95.01g2

=νχ

=

25000 25500 260000.2

0.4

0.6

0.8

1.0t=3.00 x 10-2 at/b Measurement

FIT

Tras

nmis

sion

Neutron Energy / eV

0.2

0.4

0.6

0.8

1.0 Measurement FIT

Tras

nmis

sion

t = 1.60 x 10-2 at/b

25000 25500 260000.2

0.4

0.6

0.8

1.0t=3.00 x 10-2 at/b Measurement

FIT

Tras

nmis

sion

Neutron Energy / eV

0.2

0.4

0.6

0.8

1.0t = 1.60 x 10-2 at/b Measurement

FIT

Tras

nmis

sion

25.22g2

=νχ

=

nthint ngA Γ∝,

ΓΓ∝ nthick,t ngA

)1I2(21J2g

++

=

P. Schillebeeckx, IRMM

Simplified schematic of neutron transmission

• For transmission, separate measurements of sample in and sampleout

dN TeT σ−=

Fission chamber

Elec

tron

Bea

m

Neutron ProductionTarget (water cooled)

Collimator

9 m

18 or 80 or 200 m

Neu

tron

s

Sample

Blank

Filters

Li-glass, NE1106T.O.F.

Transmission Setup at ORELA

1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 00 .0

0 .2

0 .4

0 .6

0 .8

1 .0

Tra

nsm

isio

n

N e u t r o n E n e r g y [ k e V ]

New & Improved ORELA Transmission Apparatus

• Transient digitizer (Acqiris DC-270) replaced old CAMAC TDC and several NIM modules.

• Allows simultaneous measurement of time of flight and pulse heightPrevious system for 6Li-glass detector was 1-D (TOF only), and for NE-110 detector had only 4 pulse-height channels.Allows simultaneous use of both types of detectors.

• Unlimited stops per startPrevious system limited to 8 stops/start (LeCroy 4208 TDC)

• Fewer NIM and CAMAC modulesSimpler and more reliable

Test of New Transmission Apparatus: 95Mo

Pulse Height vs. TOF vs. Counts in Region Near “Black” Resonance at 45 eV

6Li-glass detector at 80 mORELA at 525 Hz, 8 ns pulse width and 4 kW powerComputer-controlled cycling between 95Mo, blank, Bi, and CH2samples

(n,α) measurements for explosive nucleosynthesis calculations

• Improve α+nucleus potential for explosive nucleosynthesis calculations

• Compensated ion chamber (CIC) on FP 11, L = 8.9 m CIC suppresses γ flash. Allows measurements to much higher energies, larger samples (10 cm dia.), and high efficiency for measuring small (σave≈10 µb) cross sections64Zn(n,α) meas. in progress

Inside of Main CIC Detector

ORELA capture data for 41KCl compared to JENDL3.3Several resonance areas too large (neutron sensitivity) in evaluation

20 22 24 26 28 300

1

2

3

4

10 12 14 16 18 200

1

2

3

4

capt

ure

cros

s se

ctio

n [b

]

E ne rgy [keV ]

41K C l O R E LA D a ta JE N D L P a ram e te rs

41K C l O R E LA D a ta JE N D L P a ram e te rs

Comparison of SAMMY Fits with ORELA natCl transmission data

Comparison of SAMMY Fits with ORELA natCl capture data

2 0 0 0 0 0 3 0 0 0 0 0 4 0 0 0 0 0 5 0 00 0 0 6 0 0 0 0 0

0 .0 0 1

0 .0 0 2

0 .0 0 3

0 .0 0 4

0 .0 0 5

0 .0 0 6

0 .0 0 7

Cap

ture

Cro

ss S

ectio

n [b

]

E n e r g y [e V ]

E N D F /B V I E v a lu a ti o n O R E L A D a t a

2 0 0 0 0 4 0 0 0 0 6 0 0 0 0 8 0 0 0 0 1 0 0 0 0 0 1 2 0 0 0 0 1 4 0 0 0 01 E - 4

1 E - 3

0 . 0 1

0 .1

1

C

aptu

re C

ross

Sec

tion

[b]

E n e r g y [e V ]

E N D F / B V I E v a l u a t io n O R E L A D a t a

500 510 520 530 540 550 560 570 580 590 600 610

Neutron Energy (keV)

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

0.018

0.020

Cap

ture

Cro

ss S

ectio

n (b

)

ORELA data 1999ENDF/B-VI

Recent ORELA capture data compared to evaluationsSeveral resonance areas are too large (neutron sensitivity?) andresonances are missing in evaluations

30 40 50 60

Neutron Energy (keV)

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

Cap

ture

Cro

ss S

ectio

n (b

)

ORELA data 1999ENDF/B-VI

0.380 0.385 0.390 0.395 0.400 0.405 0.410 0.415 0.4200

5

10

15

20

25

30

35

40

45

50

55

60

65 ORELA data ENDF data

σ(n,

γ) (b

)

Energy (keV)5 .7 5 . 8 5 .9 6 .0 6 . 1 6 .2

0 .0

0 .2

0 .4

0 .6

0 .8

1 .0 O R E L A d a ta J E N D L d a ta

σ(n,

γ) (b

)

E n e rg y (k e V )

AlSi Cl

1 . 1 0 1 . 1 1 1 .1 2

0

2

4

6

8

1 0

O R E L A d a t a E N D F d a ta

σ(n,

γ) (b

)

E n e rg y ( k e V ) 2 . 0 0 2 .0 1 2 . 0 2 2 . 0 3 2 .0 4 2 . 0 5 2 .0 6

0

2

4

6

8

1 0 O R E L A d a ta E N D F d a t a

σ(n,

γ) (b

)

E n e rg y ( k e V )9 .0 9 .1 9 . 2 9 . 3 9 .4 9 .5 9 . 6 9 . 7 9 .8 9 .9 1 0 .0

0 .0

0 .5

1 .0

1 .5

2 .0

2 .5

3 .0

3 .5

4 .0

O R E L A d a ta E N D F d a t a

σ(n,

γ) (b

)E n e r g y ( k e V )

4 .2 0 0 4 .2 2 5 4 .2 5 0 4 .2 7 5 4 . 3 0 00

2

4

6

8 O R E L A d a t a E N D F d a t a

σ(n,

γ) (b

)

E n e r g y ( k e V )

Cl

Si

FF

KK

K

Recent (n,γ) and Transmission for 53Cr

1 1 0 1 0 0

1 E - 4

1 E - 3

0 . 0 1

0 . 1

1

1 0

σ(n

,γ) [b

]

N e u t r o n E n e r g y [ k e V ]

O R E L A d a t a E N D F - V I I

1 1 0 1 0 0

0 . 0

0 . 2

0 . 4

0 . 6

0 . 8

1 . 0

Tran

smis

sion

N e u t r o n E n e r g y [ k e V ]

O R E L A D a t a E N D F / B - V I I

Recent (n,γ) and Transmission for natural Ti

1 1 0 1 0 0

0 . 0

0 . 5

1 . 0

Tran

smis

sion

N e u t r o n E n e r g y [ k e V ]

E x p e r i m e n t a l t r a n s m i s s i o n f o r n a t u r a l T i T r a n s m i s s i o n c a l c u l a t e d f r o m E N D F / B - V I I

1 1 0 1 0 0

0 . 0

0 . 2

0 . 4

0 . 6

0 . 8

1 . 0

(n,γ)

[b]

N e u t r o n E n e r g y [ k e V ]

N a t u r a l T i ( n , γ ) d a t a E N D F / B - V I I p a r a m e t e r s

Recent (n,γ) and Transmission on 48Ti

1 1 0 1 0 0- 0 . 1

0 . 0

0 . 1

0 . 2

0 . 3

0 . 4

0 . 5

0 . 6

0 . 7

0 . 8

0 . 9

1 . 0

(n,γ)

[b]

N e u t r o n E n e r g y [ k e V ]

4 8 T i ( n , γ ) E N D F / B - V I I

1 1 0 1 0 0

0 . 0

0 . 2

0 . 4

0 . 6

0 . 8

1 . 0

Tran

smis

sion

E n e r g y [ k e V ]

T r a n s m i s s i o n E N D F / B - V I I p a r a m e t e r s

Comparison of the new ORNL 58Ni evaluation with experimental (n,γ) data

10 20 30 40 50 60 70 80 90 100

0.01

0.1

1

(n,γ)

[b]

Energy [keV]

58Ni (n,γ) data SAMMY fit

Personnel•ORELA: C. Ausmus, D.R. Brashear, T.S. Bigelow, K.H. Guber, J.A. Harvey, P.E. Koehler, J.A. White, D. Wiarda

•Nuclear Data Group:M. Dunn, G. Arbanas, K.H. Guber, H. Derrien, L.L. Leal, N.M. Larson, R.O. Sayer, D. WiardaORELA Personnel

Summary

•Neutron Energy Resolution•Perform new total and capture cross section measurements for the NCSP, i.e. 63Cu, 65Cu,

•Continue nuclear astrophysics experimentsFinish 95Mo(n,γ) and σt, 64Zn(n,α)Future experiments include (n,γ) and σt for 86,87Sr and 149Sm(n,α)

Capture and transmission are not always complementary

• Capture (thin):

• Transmission (thin):

ΓΓΓ

∝ γγ

nngA

nΓ<<Γγ nΓ>>Γγ

thintA ,

nngΓ∝

nngΓ∝

γΓ∝ ng

nngΓ∝

complementary

combine capture and transmission measurementswith different sample thicknesses