σγ / k0 measurements at Budapest PGAA facility

Zsolt Révay, László Szentmiklósi

Institute of Isotopes

Budapest

Practice of PGAA in Budapest

• k0 method

– Relative standardization

• Inelastic neutron scattering (n,n’γ) background– Using Hypermet

• Handling asymmetric peaks and overlaps

– Non-linearity– Efficiency

Why k0 method?

• Most accurate source of needed data

• k0 philosophy guarantees the highest reliability in measurements

• k0 idea can be better approximated in a beam

• Should be improved

Advantages of measurements in (cold) neutron beam

• No epithermal neutrons

• No non-1/v behavior (in cold beam)

• Lambert-Beer type self-shielding (low-divergence beam instead of isotropic neutron field)

• 20 MW

• water cooled

• water moderated

• thermal flux

1014 cm-2 s-1

Research Reactor

Neutron guides

• Ni or supermirror guides

• relatively small losses

• low background

Cold neutron

source at Budapest

400 cm3 20 K liquid H2

Budapest PGAA facilityC o n c re te

L e a d

A l tu b e

Va c u u m f it t in gL i-p o ly m e r

B G O C o m p to n su p p re s so r

• 10 MW• LH cold source• curved guide• Compton-

suppressed HPGe

• chopper

Budapest PGAA and NIPS facilities

PGAA facility

Compton suppression

2000 4000 6000 8000 10000 12000 14000 160001

10

100

1k

10k

100k

1M

Co

un

ts/C

ha

nn

el

Channel number

2000 4000 6000 8000 10000

1

10

100

1k

10k

100k

1M

E (keV)

1992 upgraded reactor starts1995 first PGAA measurement on the thermal beam1997–1998 establishment of PGAA data library1999–2000 applications2001 new cold beam2002 –2004 Handbook and Atlas

Main results in methodology• Data library transportable to other labs

• evaluation software

• complete analysis– analytical precision for the important

elements relative uncertainty: 1–2%

• application of chopped beam

Hypermet-PC

Hypermet-PC

• Asymmetric peak shape

• Non-linearity

• Efficiency fit

• Partial peak shape calibration

Efficiency

• One absolute source

• Lines from relative sources are normalized to it

• 200-300 data points

• 0.2% uncertainty at mid energy range

• 2% uncertainty at high energy range

Semiempirical efficiency function

102

103

104

10-6

10-5

10-4

10-3

Eff

icie

ncy

Energy (keV)

dead layer Al window total efficiency full-energy eff. photo single Compton multiple Compton pair

e-3 e-2 e-1 e0 e1 e2

Resid

uals

-3

0

3

Energy (MeV)

0.1 1 10

Efficien

cy

10-5

10-4

10-3

Ba-133Eu-152Bi-207Na-24N-15Poly8

Measured efficiency

Incorrect linear interpolation of the efficiency

0.02

0.025

0.03

0.035

0.04

0.045

0.05

100 1000 10000

energy (keV)

effi

cien

cy*E

^0.

73

1997-1999

2004

linear

The “elbow” of the efficiency

0.042

0.042435

0.04287

0.043305

0.04374

0.044175

0.04461

100 1000 10000

energy (keV)

effi

cien

cy*E

^0.

73

Prompt k0 project

Measurements of elements1 H

O1 D

O

2 He

3 Li

CO3,C-F

4 Be* O

5 B

C, H-O

6 C**

H

7 N

C-D-O,NO3

8 O

H, Be

9 F

C

10 Ne

11 Na* CO3 ,C-H-O

12 Mg*

13 Al** O

14 Si* O

N

15 P* O

16 S**

17 Cl

C,C-H

18 Ar*

19 K

HCO3

20 Ca* O

CO3

21 ScO

22 Ti** O

23 VO

24 Cr* O-H

25 Mn* O

26 Fe**

27 Co*

28 Ni**

29 Cu* O

30 Zn* O

31 Ga**

32 Ge* O

33 AsO

34 Se* O-H

35 Br*

C-H

36 Kr*

37 RbO

CO3

38 Sr

CO3

39 YO

40 ZrO

41 NbO

42 Mo**

43 (Tc) 44 Ru**

45 Rh*

C-H

46 Pd*

47 Ag**

48 Cd**

49 In*

50 Sn**

51 SbO

52 Te**

53 I*

C-H

54 Xe

F

55 CsO

56 Ba

OH,CO3

57 LaO

72 Hf* O

73 Ta* O

74 WO

75 Re*

76 Os* O

C-H

77 Ir* O

78 Pt*

79 Au*

80 Hg** O

81 Tl*

82 Pb**

83 Bi**

84 (Po) 85 (At) 86 (Rn)

87 (Fr) 88 (Ra) 89 (Ac)

58 CeO

C-H-O

59 PrO

60 NdO

61 (Pm) 62 SmO

63 EuO

64 GdO

65 TbO

66 Dy*

67 HoO

68 ErO

69 TmO

70 YbO

71 LuO

90 Th

NO3

91 (Pa) 92 UO

C-H-O

Standardization1 Halap

1 D

H

2 He

3 Li

C,N

4 Be

N, O

5 BH

6 CH

N

7 NH Cl

8 OH

9 F

K,C,Ca

10 Ne

11 NaH Cl

S B

12 MgH Cl

S,Fe*B

13 AlH Cl

S,Fe*B

14 SiN O

Fe*

15 PH

Na

16 SH

Na, Al

17 Cl3H

B

18 Ar

absz: Cl

19 KH Cl

B

20 CaCl

Fe*

21 ScH

S,Ti B

22 TiCl

23 VH

B

24 CrH Cl

25 MnH Cl

B

26 Fe2Cl

27 CoH Cl

B

28 NiH Cl

B

29 CuH Cl

30 ZnCl

B

31 GaH

N B

32 Ge

Co B

33 AsH

Na B

34 SeH

B

35 BrH Cl

B

36 Kr

37 RbCl

B

38 SrCl

B

39 YCl

B

40 ZrCl

N

41 NbCl

42 MoCl

43 (Tc) 44 RuH Cl

45 RhH Cl

46 PdCl

47 AgH Cl

48 CdH Cl

49 In

Sb B

50 SnH Cl

51 Sb

S

52 TeH Cl

53 IH Cl

54 Xe

F

55 CsCl

56 BaH Cl

57 LaCl

72 HfH Cl

73 TaH

Ti,H

74 WH

Na

75 ReCl

76 OsH

77 IrCl

78 PtCl

79 AuH Cl

80 HgCl

81 Tl

S

82 PbCl

N

83 BiCl

84 (Po) 85 (At) 86 (Rn)

87 (Fr) 88 (Ra) 89 (Ac)

58 Ce

H

C

59 Pr

H

S

60 Nd

H

S

61(Pm) 62 Sm

H

S

63 Eu

H

S B

64 Gd

H

S

65 Tb

H

S

66 Dy

H

S

67 Ho

H

S

68 Er

H

Cl

69 Tm

H

S

70 Yb

H

71 Lu

H

S

90 ThHN B

91 Pa 92 UHC B

PGAA libraryZ El A MW # E dE d% RI Area cps/g1 H 1 1.01 1 2223.259 0.019 0.3326 0.2 100.00 100.00 64.1831 H 2 1.01 2 6250.204 0.098 0.000492 5.0 0.15 5.00 0.02863 Li 6 6.94 5 477.586 0.050 0.001399 5.9 3.52 10.14 0.12183 Li 7 6.94 2 980.559 0.046 0.004365 5.1 10.97 18.74 0.22513 Li 7 6.94 3 1051.817 0.048 0.004364 5.1 10.97 17.83 0.21413 Li 7 6.94 1 2032.310 0.070 0.0398 5.0 100.00 100.00 1.20073 Li 6 6.94 6 6769.633 0.263 0.001354 6.5 3.40 0.84 0.01013 Li 6 6.94 4 7246.800 0.275 0.002106 8.4 5.29 1.17 0.0144 Be 9 9.01 4 853.631 0.011 0.00165 8.9 26.69 100.00 0.07234 Be 9 9.01 3 2590.014 0.025 0.00188 8.9 30.41 49.08 0.03554 Be 9 9.01 2 3367.484 0.035 0.002924 8.9 47.30 58.96 0.04274 Be 9 9.01 5 3443.421 0.036 0.000993 8.9 16.06 19.54 0.01414 Be 9 9.01 6 5956.602 0.092 0.000146 9.1 2.36 1.41 0.0014 Be 9 9.01 1 6809.579 0.099 0.006181 9.0 100.00 48.52 0.03515 B 10 10.81 1 477.600 5.000 712.5 0.3 100.00 100.00 398066 C 12 12.01 2 1261.708 0.057 0.00123 2.7 45.58 100.00 0.03066 C 12 12.01 3 3684.016 0.069 0.001175 3.5 43.53 38.02 0.01166 C 12 12.01 1 4945.302 0.066 0.002699 2.9 100.00 60.55 0.01867 N 14 14.01 22 583.567 0.031 0.000429 3.3 1.81 6.93 0.01597 N 14 14.01 12 1678.244 0.029 0.006254 1.5 26.34 47.15 0.10857 N 14 14.01 18 1681.174 0.043 0.001296 2.7 5.46 9.76 0.02257 N 14 14.01 21 1853.944 0.052 0.000474 4.5 2.00 3.31 0.00767 N 14 14.01 5 1884.853 0.031 0.0145 1.3 61.07 100.00 0.23017 N 14 14.01 24 1988.532 0.077 0.000294 5.8 1.24 1.94 0.00457 N 14 14.01 15 1999.693 0.032 0.003208 1.7 13.51 21.12 0.04867 N 14 14.01 13 2520.446 0.039 0.004246 1.8 17.88 22.98 0.0529

Verification1 Hkompoldatok

1 D

H

2 He

3 Li 4 Be 5 BH,üveg

GEO

6 Ckarbo-nátok

7 Nkomp

8 Ooxidok

9 FCa

10 Ne

11 Nakomp

üveg

12 Mgüveg

13 Alcem,kat,GEO

14 Siüveg,kat,GEO

15 PH

Na

16 SkompcemGEO

17 Clkomp

18 Ar

19 KSRM

20 CaSRM,cem

21 Sc 22 TiCl

GEO

23 Vkat

24 CrSRM,

kat

25 MnSRM

GEO

26 FeSRM,GEO

27 Cooldat

28 Nikat,fémüveg

29 CuAg-Cu

30 Zn 31 Ga 32 Ge 33 As 34 Se 35 Br 36 Kr

37 RbB38 Sr 39 Y 40 Zr

fémüveg41 Nbkat

42 Mokat

43 (Tc) 44 Ru 45 Rh 46 Pdfémüveg

47 AgAg-Cu

48 CdSRM

GEO

49 In 50 SnSn-Cd

51 Sb 52 Te 53 I 54 Xe

55 Cs 56 Ba 57 La 72 Hf 73 Ta 74 W 75 Re 76 Os 77 Ir 78 Ptkat

79 Aukomp

80 Hg 81 Tl 82 PbPb-Cd

83 Bi 84 (Po) 85 (At) 86 (Rn)

87 (Fr) 88 (Ra) 89 (Ac)

58 Ce 59 Pr 60 Nd 61(Pm) 62 Sm 63 Eu 64 Gd

üveg,GEO

65 Tb 66 Dy 67 Ho 68 Er 69 Tm 70 Yb 71 Lu

90 Th 91 Pa 92 U

Prompt k0 factors

• relative to Cl 1951 keV line• relative to H 2223 keV line

• σγ = θ γ σ

x

c

cc

xx

x

c

c

xc n

n

A

A

M

Mk

/

/

,

,,0

Decay gammas in PGAA spectra

• can be used for analysis, too

• k0-s can be measured

• depending on half-life, saturation correction needed

Prompt saturation factor

• activation and decay at the same time

11

teB

t

Activation

0 1 2 3 4 5 *t

rel.

nu

mb

er

of

cou

nts

promptdecayshifted prompt

Advantages of the in-beam measurement compared to

cyclic activation• uncertainties from

– half-life– timing

do not accumulate

k0-s for short lived nuclidesFinal

nuclide

Energy

(keV)Half-life Theoretical k0

8k0

De Corte et al1

k0

Roth et al2

k0

present work

20F 1633.6 11.03 0.06 s (1.060.05) 10–3 (1.010.007) 10–3 (1.060.04) 10–3

24mNa 472.28 20.2 0.1 ms (4.820.05) 10–2 (3.630.02) 10–2 (4.340.03) 10–2

28Al 1778.99 2.2414 0.0001 m (1.79 0.02) 10–2 (1.750.01) 10–2 (1.800.02) 10–2

38mCl 671.33 0.715 0.003 s (6.7 1.4) 10–3 (7.950.14) 10–4 (7.60.8) 10–4

46Sc 142.53 18.7 0.05 s 0.282 0.033 0.227.002 0.226 0.002

51Ti 320.08 5.76 0.01 m (3.77 0.07) 10–4 (3.740.04) 10–4 (3.660.11) 10–4

52V 1434.08 3.75 0.01 m 0.2 0.005 0.196 0.002 0.197 0.004

56Mn 846.81 2.5785 0.0006 h 0.5 0.008 0.496 0.030 0.502 0.006

60mCo 1332.5 10.47 0.006 m 3.3 10–3 (3.200.09) 10–3

66Cu 1039.35 5.088 0.011 m (1.60.4) 10–3 (1.860.009) 10–3 (1.970.04) 10–3

77mGe 215.48 52.9 0.6 s 2.69 10–5 (2.68 0.13) 10–5

77mSe 161.92 17.45 0.1 s 0.0290.001 (2.570.001) 10–2 (2.240.04) 10–2

Chopped-beam PGAA

TOF

Beam chopper

• Variable opening: 0.2 – 50%

• variable frequency: 3 – 100 Hz

• Beam periodically shielded by Gd, 6Li

Time of flight

n

gamma radiation

detectorchopper

Rotating and standing slits

Cold and thermal neutron spectra

Wavelength spectra of thermal and cold beams

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

0 5 10 15 20

wavelength (AA)

TN1

CN1

Candidates for in-beam measurement

< 1 s: Na,

< 1 min: F, Sc, Ge, Pd, Ag, In, Er, Hf, W,

< 10 min Mg, Al, V, Cr, Se, Br, Rh, Dy, Ir,

< 1 h: Ga, Rb, Sn, I, Pr, Nd, Ta, Re,

<1 day: Mn, Cu, Sr, Cs, Ba, Eu, Lu,

longer: As, Ru, La, Ce, Tb, Ho, Yb, Au,

Isotopes with high Er

Q0 Er Isot sigma1.12 2280 37S 0.151.14 1040 64Cu 2.171.908 2560 65Zn 0.762.38 3540 75mGe 0.171.57 3540 75Ge 0.345.93 4300 90mY 0.0015.05 6260 95Zr 0.04991.8 2950 131I 6.21.2 1540 143Ce 0.95

First prototype of chopper

Budapest PGAA facility (L. Sz.)

Simultaneous PGAA and NAA measurement with a chopper

• Beam open

prompt gamma rays

decay gamma rays

Usual PGAA spectrum

• Beam closed

only decay gamma rays

cyclic NAA spectrum

21

14

Mn

18

48

18

11

Mn

17

79

Al

15

13

13

64

13

26

11

31

10

268

47

Mn

82

3

69

0

51

1 A

nn

ih.

59

0

90

Tc-

99

53

8

12

01

172 Tc-100 p

1E-5

1E-4

1E-3

1E-2

1E-1

1E+0

1E+1

1E+2

0 500 1000 1500 2000 2500

E [keV]

Co

un

t ra

te [c

ps

]

Tc-100 decay

Tc-99 capture

Prompt and decay spectrum of Tc-99

Name Reactor Beam Vacuum Chopper Phase Backgound

(cps)

Room background off – – – – 0.63

Beam-off background on off – – – 1.5

Beam-on background

(in vacuum)

on on yes – – 4.0

Beam background in air on on no – – 5.6

Chopper background in

prompt phase

on on no on prompt 5.3

Chopper background in

decay phase

on on no on decay 4.6

Background

prompt spectrum decay spectrum gainEl E (keV)

rate S/N rate S/N

F 1633 1.63(2) 1300 1.63(6) 7000 5

Al 1779 2.62(1) 2000 2.61(1) 200,000 100

Sc 143 28(1) 200 29(1) 40,000 20

147 46.8(7) 400

V 125 20.0(2) 270

1434 9.3(1) 1200 8.8(4) 41,000 34

Cu 159 29.6(2) 200

1039 0.58(2) 90 0.55(2) 900 10

Ag 198 82(1) 62

658 7.16(15) 20 7.3(3) 1900 95

In 163 157(3) 53 146(6) 3700 70

Er 185 32(1) 400

208 14.6(8) 180 15.4(6) 11,000 60

Mea-sure-ments

0.0001

0.001

0.01

0.1

1

10

100

0 1000 2000 3000 4000 5000 6000E (keV)

Inte

nsity

(cps

)

prompt

decay

background

Spectra

0.001

0.01

0.1

1

10

600 620 640 660 680 700

E (keV)

Inte

nsi

ty (

cps)

promptdecay

108Ag 110Ag

Prompt and decay spectrum of Ag

ResultsElement Half-life Energy (keV) decay

line

(barn)

prompt line

(barn)

F 11.16 s 1633 0.0093(3) –

Al 2.24 m 1779 0.233(4) <0.005

Sc 18.75 s 143 4.88(10) <0.13

V 3.75 m 1434 5.20(10) <0.3

Cu 5.12 m 1039 0.0600(12) <0.0023

Ag 24.6 s 658 1.93(4) <0.08

In 2.18 s 163 15.8(8) <1.1

Er 2.27 s 208 2.15(9) <0.18

Second prototype chopper

In-beam saturation factor (B) (LSz)

11

mt

m

eB

t

Type I nuclides, on-line counting

3 3 3233 1 2

3 2

( ) 1 1t t ttm gdR t N E F e e e e

Count rate of #3 from Bateman-Rubinson equations:

3 23

2 22 3

23 3 2 2 3

1 111 1

m mm

t tmt

gm m

e eeB F

t t

Type IV nuclides Type IV/B

nuclides

Type IV/A nuclides

Results 1/3 (LSz)

Sample Nuclide Energy, keV

k0,Au (Rel. unc %)

Literature Z-score

PTFE cylinder 20F 1633 0.00102 (2.2%) 9.98E-4 (1.2%) 1.01E-3 (0.7%)

0.87 0.44

Na2S2O3.5H2O 24Na 1369 0.047646 (1.8%) 4.68E-02 (0.6%) 0.94 2754 0.047591 (2.2%) 4.62E-02 (0.8%) 1.26 Al(OH)3

28Al 1779 0.017946 (1.1%) 1.75E-02 (0.8%) 1.80 MnCl2.4H2O 38mCl 671 0.000791 (5.1%) 7.95E-04 (1.7%) -0.09 38Cl 1642 0.00202 (6.1%) 1.97E-03 (1.4%) 0.43 2167 0.00280 (4.8%) 2.66E-03 (1.3%) 1.01 56Mn 847 0.499 (1.0%) 4.96E-01 (0.6%) 0.54 1811 0.1351 (1.1%) 1.35E-01 (0.4%) 0.09 2113 0.0728 (1.8%) 7.17E-02 (0.2%) 0.83 Sc2(SO4)3

46Sc 143 0.225 (2.1%) 0.2270 (0.7%) -0.42

Literature data taken from:F. De Corte, A. Simonits, Atomic Data and Nuclear Data Tables 85 (2003) 47.S. Roth, F. Grass, F. De Corte, L. Moens, K. Buchtela, J. Radioanal. Nucl. Chem. 169 (1993) 159.S. Van Lierde, F. De Corte, D. Bossus, R. Van Sluijs, S. Pommé, Nucl. Instr. Meth. A 422 (1999) 874.

Results 2/3 (LSz)

Sample Nuclide Energy, keV

k0,Au (Rel. unc %)

Literature Z-score

KBr+H2O 80Br 616 0.00675 (1.5%) 6.92E-03 (0.3%) -1.71

666 0.00122 (2.3%) 1.22E-03 (0.5%) -0.04

82Br 554 0.02315 (1.9%) 2.38E-02 (1.1%) -1.28 619 0.01387 (2.0%) 1.45E-02 (0.8%) -2.11 698 0.00917 (2.2%) 9.38E-03 (0.9%) -0.98 777 0.02756 (1.4%) 2.76E-02 (0.8%) -0.10 828 0.00753 (3.1%) 7.99E-03 (0.9%) -1.87 1044 0.00872 (2.7%) 9.14E-03 (0.7%) -1.71 1317 0.00828 (3.0%) 8.91E-03 (0.4%) -2.54 1475 0.00536 (3.5%) 5.42E-03 (0.5%) -0.33 KI+H2O 127I 443 0.0117 (0.9%) 1.12E-02 (1.7%) 2.12 527 0.0011 (2.0%) 1.07E-03 (1.4%) 1.40 HfOCl2.8H2O 179m1Hf 214 0.176 (1.6%) 0.1770 (0.2%) -0.36

Results 3/3 (LSz)

Sample Nuclide Energy, keV

k0,Au (Rel. unc %)

Literature Z-score

H2WO4 187W 134

0.0117 (1.6%) 1.13E-02 (0.7%) 2.04 478 0.0299 (1.4%) 2.97E-02 (1.0%) 0.34 552 0.00693 (1.4%) 6.91E-03 (0.5%) 0.21 618 0.00856 (1.4%) 8.65E-03 (0.7%) -0.64 625 0.00151 (2.2%) 1.48E-03 (–) – 686 0.0379 (1.6%) 3.71E-02 (0.5%) 1.21 773 0.00563 (1.4%) 5.61E-03 (0.7%) 0.19 RbNO3+H2O 86mRb 556 0.000999 (2.1%) 9.96E-04 (1.6%) 0.13 88Rb 898 0.00011 (4.8%) 1.01E-04 (1.5%) 2.32 1836 0.00017 (5.2%) 1.57E-04 (1.1%) 0.97 AgNO3+H2O 108Ag 434 0.00168 (4.8%) 1.59E-03 (2.0%) 1.07 619 0.00105 (6.7%) 9.33E-04 (0.8%) 1.72 633 0.00585 (1.6%) 6.01E-03 (0.8%) -1.50 110Ag 658 0.03627 (1.2%)=

1.881 b (1.2%) 1.93 b (2.1%)

1.06

Cross-section measurements for fissile material

• Uranium– 235U– 238U– Fission products

• Thorium – still going on

Conclusion

• In-beam activation can be used for σγ /k0 measurements– No epithermal activation– Short lived nuclides can be measured well– Simple self-shielding– No resonances in cold beam