Measurement of Neutron Total Cross Sections of Natural Hafnium and Tantalum at Pohang Neutron...

Measurement of Neutron Total Cross Sections of Natural Measurement of Neutron Total Cross Sections of Natural Hafnium and Tantalum at Pohang Neutron Facility Hafnium and Tantalum at Pohang Neutron Facility

Measurement of Neutron Total Cross Sections of Natural Measurement of Neutron Total Cross Sections of Natural Hafnium and Tantalum at Pohang Neutron Facility Hafnium and Tantalum at Pohang Neutron Facility

Course Title: Experimental Method and Data Process

Respected Professor Kihyeon Cho

Prepared By:

A.K.M. Moinul Haque Meaze

Student ID: 2003419008

Department of Physics

Kyungpook National University

Republic of Korea

The 23rd March, 2004 -0- Preparation For KPS Spring MeetingThe 23rd March, 2004 -0- Preparation For KPS Spring Meeting

We have measured neutron total cross sections of natural hafnium (Hf) and tantalum (Ta) in the neutron energy region from 0.1 eV to 100 eV by using the time of flight method at the Pohang Neutron Facility (PNF). The PNF consists of an 100 MeV electron linac, a water cooled Ta target, four position automatic sample changer controlled remotely by CAMAC data acquisition system, and a 6LiZnS(Ag) glass scintillator as a neutron detector. The distances from the water cooled Ta target to the sample changer and to the scintillator are 5.4m and 10.8m respectively. Notch filter consists of Cobalt (Co), Indium (In) and Cadmium (Cd) which has a large resonance peaks in the spectrum to determine the background levels. To reduce gamma flash originated from the neutron target we have employed a neutron-gamma separation system based on their different pulse shape. Resonance parameters were determined with the computer code SAMMY which utilizes both Doppler and resolution broadening effects and Bayes' generalized least squares technique. The present total cross sections were compared with evaluated data in ENDF/B-VI.8 and the previous experimental data. The resonances parameters were compared with Landolt-Börstein’s data.

ABSTRACT ABSTRACT ABSTRACT ABSTRACT


• Information about the relative probabilities of different reactions provides clues to the problem of nuclear structure and offers a testing ground for ideas about nuclear forces. So cross section is used to obtain information about the internal structure of atomic nuclei and their constituents.

• The possibility of achieving a chain reaction and to design and development of a nuclear reactor depend strongly on the values of neutron cross section in the thermal energy region. So depending on the values of total neutron cross sections we may use the materials in the reactor.

Name of the Sample

Area(cm2)

Thickness, t(a/b)

Atomic weight, A(amu)

Density, ρ(g-cm-3)

Atomic density, N (cm-2)

HafniumTantalum

5x55x5

0.002210.02217

91.22180.95

13.3016.65

2.24x1021

2.21x1021

INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION

CHARECTERISTICS OF SAMPLES USED IN THIS EXPERIMENT CHARECTERISTICS OF SAMPLES USED IN THIS EXPERIMENT CHARECTERISTICS OF SAMPLES USED IN THIS EXPERIMENT CHARECTERISTICS OF SAMPLES USED IN THIS EXPERIMENT


Ta target

11

1030

30

30

Water Moderator Pb

Fe

Al

Linac

10 Ta Plates

- 3 (40 mmx 2mm t)

- 2 (40 mmx 3mm t)

- 1 (40 mmx 4mm t)

- 4 (40 mmx 6mm t)

with 2 mm t Ti cover

Ta161(,n)Ta160

Linac

Linac

Targ

et

Targ

et

Modera

tor

Size

Modera

tor

Size

Modera

tor

Modera

tor

INSTROMENTS INSTROMENTS INSTROMENTS INSTROMENTS


INSTROMENTS(CONTINUED) INSTROMENTS(CONTINUED) INSTROMENTS(CONTINUED) INSTROMENTS(CONTINUED)


Experim

enta

l Setu

p

Oute

r side o

f TO

FSam

ple

C

hanger

)(ln1

)( TNt

E

)}()({

)}()({)(

BGOB

BGSBT

2

2

}){(

)3.72(

tI

LE

F

I

F

I

E

E

E

Eeff

dE

EdEE

.

A

tNN A

tEt

LI

3.72

)(1 2

XYXYX

)(1

YXXYNL

EX

3.72 tIY

22 )( XXN

J c

cJccc

JcccJT XXg

kE )}2sin()Re()2cos()Im({sin

4)( 2

2

SEE GE

S

GE

GE

EEEEEdEEER

2

2000 '

expexp1

',

2/1baEEG

2/3cEE

bxay

1)(2 dIIyN

})(4{

2220

cxxw

Awyy

USED EQUATIONS USED EQUATIONS USED EQUATIONS USED EQUATIONS


OBSBTstat

11

)ln(

1

1000 2000 3000

0

100

200

300

400

500

Data: Data1_BModel: LineEquation: y = A + B*xWeighting: y No weighting Chi^2/DoF = --R^2 = 0 A 5.85526 ±--B -0.00181 ±--

Counts

Channel No(5S/Ch)

Notch Filter Open Fitting Function

500 1000 1500 2000 2500 3000

0

500

1000

1500

2000

2500

3000

Counts

Channel No(0.5S/Ch)

Hf Sample Open Normalized Fitting Function

1000 2000 3000 4000

0

2000

4000

6000

Counts

Channel(0.5S/Ch)

Ta Sample Open Normalized Fitting Function

ANALYZED DATA ANALYZED DATA ANALYZED DATA ANALYZED DATA


Background level determination with Co, In, and Cd samples.

Hf In &

Out w

ith Background

Ta In

& O

ut w

ith B

ackg

rou

nd

500 600 700 800200

400

600

800

1000

Counts

Channel(0.5S/Ch)

fit-2

E=6.3

2413eV

1200 1400 1600 1800 2000

100

200

300

400

500

600

E=1.0

5559eV

Counts

Channel(0.5S/Ch)

fit4

400 500 600 700 800 900200

400

600

800

1000

E=7.3

7647eV

fit-1

Counts

Channel(0.5S/Ch)

900 1000 1100 1200

200

400

600

800

E=2.3

0332eV

fit-3

Counts

Channel(0.5S/Ch)

LORENZIAN FITTINGS LORENZIAN FITTINGS LORENZIAN FITTINGS LORENZIAN FITTINGS


Hf total cross section from TOF spectrum Hf 178.49 0.1033549 1213 9 USE NEW SPIN GROUP FORMATchi squared is wanteddo not suppress any intermediate resultsgenerate plot file atomicallytwentybroadening is wantedexponential folding

300 10.8000 0.02 0.2500 0.5000 8.18 0.0022098 0.00 0.000transmission 0.0000 0.0000 0 1 1 1 0 0.5 0.0016 0 1 1 0 0 0.5 .000 .000 2 1 0 0.5 0.0521 0 1 1 0 0 0.5 .000 .000 3 1 0 -3.0 0.18560 -3.5 1 1 0 0 3.0 .000 .000 4 1 0 -4.0 0.18560 -3.5 1 1 0 0 4.0 .000 .000 5 1 0 0.5 0.27100 0 1 1 0 0 0.5 .000 .000 6 1 0 4.0 0.13750 4.5 1 1 0 0 4.0 .000 .000 7 1 0 5.0 0.13750 4.5 1 1 0 0 5.0 .000 .000 8 1 0 0.5 0.35220 0.0 1 1 0 0 0.5 .000 .000

Ta total cross section from TOF spectrum Ta 180.948 0.14594 99.924135 3937 09 USE NEW SPIN GROUP FORMATchi squared is wanteddo not suppress any intermediate resultsgenerate plot file atomicallytwentybroadening is wantedexponential folding

300. 10.8000 0.02 0.2500 0.5000 8.2200 0.0221737 .00 0.000transmission 3.5000 0.0000 0 1 1 1 0 4.0 .99988 3.5 1 1 0 0 4.0 .000 .000 2 1 0 3.0 .99988 3.5 1 1 0 0 3.0 .000 .000

1 2 3 4 5 6 7 8400

600

800

1000

1200

1400

1600

mL )020.0800.10( S )001.0540.1( tEt

LI

3.72

1 2 3 4 5 6 7 8400

600

800

1000

1200

1400

1600

mL )020.0800.10( S )001.0540.1( tEt

LI

3.72

LEAST SQUARE FITTING AND SAMMY INPut LEAST SQUARE FITTING AND SAMMY INPut LEAST SQUARE FITTING AND SAMMY INPut LEAST SQUARE FITTING AND SAMMY INPut


Least Square Fitting

SAMM

Y Ta INPu

t

SAMM

Y Hf IN

Put

RESULTS: TOTAL CROSS SECTIONS RESULTS: TOTAL CROSS SECTIONS RESULTS: TOTAL CROSS SECTIONS RESULTS: TOTAL CROSS SECTIONS


1 10 1001

10

100

1000

10000

100000

1000000

0

2

4

6

8

10

Cro

ss S

ecti

on

(b)

Energy(eV)

Present Experiment SAMMY Fitting Results

B. Bernstein et al, 1952J.A. Harvey et al, 1955 E.G. Joki et al, 1961 ENDF/B-VI.8

1 10 1001

10

100

1000

10000

100000

Cro

ss S

ecti

on

(b)

Energy(eV)

Present Experiment SAMMY Fitting Results

E.Melkonian et al, 1953 J.A. Harvey et al, 1955 R.L. Christensen,1953 J.E. Evans et al, 1955 ENDF/B-VI.8

Measured Hf Total Cross SectionMeasured Hf Total Cross Section

Measured Hf Total Cross SectionMeasured Hf Total Cross Section

Hf IsotopeJ L

E(eV) (meV) n (meV)

174 .5 0 Present -0.989998( 1) 60.326( 2) 2.3009( 3)

Landolt-Börnstein -0.99 60.3 2.3

174 .5 0 Present 4.25013 (4) 60.298 (5) 1.7016 ( 6)

Landolt-Börnstein 4.25 60.3 0.0082

174 .5 0 Present 13.4573 ( 7) 60.639 ( 8) 4.9547(9)

Landolt-Börnstein 13.38 60.3 4.8

174 .5 0 Present 29.2845 (10) 60.411 (11) 29.415 (12)

Landolt-Börnstein 29.94(20) 60.3 4.8

174 .5 0 Present 70.4868 (13) 60.3 (14) 12.004 (15)

Landolt-Börnstein 70.5(3) 60.3 12

174 .5 0 Present 77.9282(16) 60.302( 17) 64.925( 18)

Landolt-Börnstein 77.9(3) 60.9 65

Hf Isotope J l E(eV) (meV) n (meV)

178 3 0 Present 7.52567(160) 84.520(161) 25.222(162)

Landolt-Börnstein 7.78(2) 60(10) 51(3)

Hf Isotope J L E(eV) (meV) n (meV)

180 .5 0 Present 72.5031(196) 37.432(197) 20.903(198)

Landolt-Börnstein 72.5(3) 46 55(3)

RESULTS: RESONANCES PARAMETERS OF Hf RESULTS: RESONANCES PARAMETERS OF Hf RESULTS: RESONANCES PARAMETERS OF Hf RESULTS: RESONANCES PARAMETERS OF Hf


Ta Isotope J l E(eV) (meV) n (meV)

181 4 0Present -44.0429(1) 46.470(2) 127.38(3)

Landolt-Börnstein -44 55 199.88

181 3 0Present -11.7095(31) 43.889(32) 7.4027(33)

Landolt-Börnstein -11.7 55 20.719

181 4 0Present 4.15644(4) 42.969(5) 3.2292(6)

Landolt-Börnstein 4.28(2) 53 3.20(14)

181 3 0Present 9.93338(34) 34.66(35) .58131(36)

Landolt-Börnstein 10.36(2) 65(6) 4.0(21)

181 4 0Present 13.2222(7) 140.69(8) .18499(9)


181 3 0Present 20.2148(37) 57.670(38) 3.8820(39)


181 3 0Present 22.4942(40) 203.25(41) .64941(42)


181 4 0Present 23.9448(10) 63.168(11) 2.1061(12)


181 3 0Present 31.0734(43) 41.552(44) .23283(45)


181 3 0Present 34.3316(46) 53.930(47) 0.18661(48)


181 3 0Present 33.7724(49) 196.01(50) 55.065(51)


RESULTS: RESONANCES PARAMETERS OF Ta RESULTS: RESONANCES PARAMETERS OF Ta RESULTS: RESONANCES PARAMETERS OF Ta RESULTS: RESONANCES PARAMETERS OF Ta


The present results are in good agreement with the evaluated data in ENDF/B-VI and the previous measurements. The resonance parameters of Hf and Ta isotopes have been determined by fitting the transmission data and their results are also in agreement with the previous ones. The SAMMY prediction of total cross-section and the present data are in good agreement with each other with 2/N=2.02.

CONCLUSION CONCLUSION CONCLUSION CONCLUSION


Measurement of Neutron Total Cross Sections of Natural Hafnium and Tantalum at Pohang Neutron...

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