Transcript LRT 2004 at SNO, Sudbury 12. December 2004 Low level counting from meteorites to neutrinos: spectroscopy with multi coincidence NaI systems, Ge.

LRT 2004 at SNO, Sudbury 12. December 2004
Low level counting from meteorites to neutrinos:
spectroscopy with multi coincidence NaI systems, Ge detectors
proportional counters and rare gas mass spectrometry
Gerd Heusser
Max-Planck-Institut für Kernphysik, Heidelberg, Germany
([email protected])
Outline:
or the chronology of a nerd
Thanks to the colleagues of the collaborations:
HEIDELBERG MOSCOW, GALLEX/GNO, BOREXINO, GERDA
in meteorites
without shield
(poor man space probe)
26Al
(7.16x105 y) +
22Na
60Co
only Pb shield
(2.602 y) +
(5.27 y)
R = 75 cm
Pb + Hg shield
100
Pb + Hg + veto
60Co
40
150
Jilin
4¶
meteorite
1.77 to
1a
1b
Fall
1976
detector + coincidence
condition
half of 10”Ø x 9”
total count rate [cpm] ( 100 keV)
no anticoinc.
with anticoinc.
537
167
6”Ø x 4”
201
67
2 fold coinc. 1a + 1b
214
22
3 fold coinc. 1a + 1b + 2
1.6
0.16
Prof.
Ouyang
T2¶ = 7.2 ± 1.2 My
T4¶ = 0.31 ± 0.07 My
n
2¶
The Low Level Laboratory of the MPI-Kernphysik
(since 1968)
n-induced
old ships iron
around detector
material
selection
test of
veto
systems
mBq
mBq/kg
sensitivity
Rn removal
by flushing
or pumping
inner shielding
material
plate out of 222/220Rn progenies
sequentional counting
E (keV)
background
or
Cosmogenic
production
Background components in Ge spectrometry
•
external gamma radiation (2.6 MeV 208Tl, {up to 3.2 MeV 214Bi})
•
radio-impurities close to crystal
(primordial, anthropogenic)
•
Rn and its progenies
•
cosmic rays
(neutrons, muon and activation)
•
neutrons from fission and
,n reactions
most important: material screening
U/Th chains and K dominant from Bq/kg down to Bq/kg only
reliably radiopure material - Cu – but mBq/kg cosmogenics
besides Si, Ge, Au, Ag, Hg, (Pb – except Pb-210)
improvements in iterative steps
Stimulations from:
R.L.Brozinski, PNL, F.T. Avignone, USC
Goulding et al., LBL
Ph. Hubert, CENBG
E. Fiorini and his group, INFN Milan
P. Jagam, J.J. Simpson, Guelph
R. M. Lindstrom, NIST
238U
decay chain
mass
spectrometry
gamma active nuclides
sub chains
highly
volatile
also from
atmospheric
deposition
if Rn can escape,
(plate out activity)
otherwise Rn and
Ra included
232Th
decay chain
gamma active nuclides
mass spectrometry

sub chain
if Rn can escape,
(plate out activity)
otherwise Rn and
the progenitors up
to 228Th included
LNGS
71Ga
(e, e-)71Ge
T1/2= 11.4 d
Ray Davis type
miniature proportional
counter
together with
M. Hübner
R. Schlotz
(1980)
69Ge
(T1/2 39.0 h)
 + + decay
Ralf Lackner
movable miniture
X-ray generator
Marcim Wójcik
composition of background for Fe cathode counters in Pb/Cu shield at LNGS
All GNO runs
recorded during
the first 50 days
Fe powder
screened
Background rates for counters used in GNO (0.5 keV  E  15 keV) : 0.45
(8 with Fe cathode and 12 with Si cathode)
With pulse shape discrimination [counts/d]
L-window fast
K-window fast
0.040
0.025
some contamination
introduced during
assembly (glassblowing)
40 Bq/m3 222Rn
1.2 Bq/m3 85Kr
1 mBq/m3 39Ar
7Be

+e-
+e-
80 Bq/m3 222Rn
100 nBq/m3 39Ar/85Kr
Commitment of
Heidelberg
develop methods to detect noble gas radionuclides
and 226Ra (via 222Rn) at the Bq level
screen relevant materials and subsystems at that level
provide nitrogen for scint. purification at the req. level
a
concentration
of Rn
b
proportional
counting
sensitivity = f(procedure blank)
M. Laubenstein, Y. Zakharov
W. Rau, B. Freudiger
H.
Simgen, Ch. Buck, G. Zuzel
N2
H2O
emanation
222Rn
(226Ra) assay with proportional counting
Ray Davis Jr.
type
miniture
counter
efficiency for internal counting ( 15 keV): 148 %
background: 0.2 – 2 counts per day
 about 30 Bq 222Rn easily detectable (monitoring)
Extract Rn from large quatities of water, nitrogen and
as an emanation signal of subsystems of BOREXINO
Reached sensitivities:
H2O: 1 mBq Ra/m3 nitrogen: 0.5 Bq/m3 surface 0.5 Bq/m2
emanation
0.1 mBq/Rn/m3
Measuring procedure for Ar and Kr
Pipes backed out and flushed
with nitrogen for some days
Metal-sealed valves
VCR
flange
Pipette
Sample
volume: ~1 ccm
gas
Sample
purification
liquid
85Kr
Mass spectrometer
conc. in air, BMU Ann. Rep.02
Dewar (200 L)
with liquid nitrogen
bubbler
G. Zuzel
H. Simgen
[Bq/ m3]
N2
6.0
1974
2001
Nitrogen plant of BOREXINO
activity in nitrogen [Bq/kg]
nitrogen sample
39
RPN2 Borexino
12
41
HPN2 Borexino
12
31
Ar a)
85
Kr a)
HPN2 Borexino liq.extr.
Linde Worms (7.0)
0.017
0.07
SOL Mantua (7.0)
0.006
0.04
Westfalen Hörstel (6.0)
0.0006
0.06
required
0.4
0.14
air
a)
b)
~1.1x104
222
Rn b)
40
0.4
 0.3
11.5 l
1
2 kg
Carbo
- Act
6
~1.2x106 ~1x107
measured by rare-gas MS; 1 ppm Ar = 1.19 Bq/kg; 1 ppt Kr = 1.03Bq/kg
measured by concentration and proportional counting
Heidelberg Moscow
76Ge  experiment
(Klapdor-Kleingrothaus et al.)
detector design in
close collaboration
with Canberra, Olen
A. Piepke
Background components from
Monte Carlo simulation
C. Dörr, HV Klapdor-Kleingrothaus
NIM A 513 (2003) 596-621
ANG2 LNGS, no shield
Heidelberg Moscow
plot from O. Chkvorets
+
137Cs
60Co
40K
U
Th
207Bi
0
plus continuous contribution
of Ge intrinsic cosmogenics
60Co
GeMPI
Ge spectrometer
of MPI at LNGS
15 l sample
chamber
B. Prokosch
H. Neder
M. Laubenstein
Cosmogenic production rate in Cu
(at LNGS surface)
radionuclide halflife specific activity [Bq/kg]
56
Co
Co
58
Co
60
Co
54
Mn
59
Fe
46
Sc
48
V
57
radionuclide
cosmogenic
26
Al
7
Be
56
Co
57
Co
58
Co
60
Co
51
Cr
52
Mn
54
Mn
22
Na
46
Sc
48
V
primordial
40
K
232
Th
238
U
M. Laubenstein
G. Heusser
preliminary
77.31 d
271.83 d
70.86 d
5.27 y
312.15 d
44.5 d
83.79 y
15.97 d
230 ± 20
1800 ± 300
1600 ± 30
2100 ± 150
210 ± 20
460 ± 90
53 ± 14
11 ± 5
halflife
Moravka 1 (214 g)
Moravka 2 (329 g)
7.16x105 y
53.3 d
77.31 d
271.83 d
70.86 d
5.27 y
27.705 d
5.591 d
312.15 d
2.602 Y
83.79 y
15.974 d
60.4 ± 3.3
43.7 ± 7.6
6.5 ± .8
16.6 ± 2.0
11.7 ± 0.8
16.1 ± 0.9
57.7 ± 8.3
12.9 ± 1.9
120.8 ± 6.2
97.4 ± 5.1
9.0 ± 0.6
20.1 ± 1.3
54.2 ± 3.0
59,2 ± 7.9
5.5 ± 0.7
12.8 ± 1.6
8.9 ± 0.8
6.3 ± 0.4
36 ± 17
102.5 ± 5.3
85.8 ± 4.5
8.2 ± 0.7
16.1 ± 3.2
1413 ± 85
9.18 ± 0.57
8.32 ± 0.7
1395 ± 83
8.93 ± 0.69
7.68 ± 0.68
1.277x109 y
1.405x1010 y
4.468x109 y
Moravka meteorite
(fall: 6.5.00)
H. Neder
G.Heusser
background (peak) count rates [c/kg y]
Energy [keV]
GeMPI HDM # 1-5
352 (U/Ra)
609 (U/Ra)
583 (Th)
2615 (Th)
1461 (K)
100-2730 keV
 31
 30
 23
17  5
90  13
9760
110 - 180
96 - 140
18 - 42
11 - 22
74 - 290
12300
Contamination of Cu [Bq/kg]
226Ra
(U)
228Th
(Th)
40K
Cryostat of ANG1
168  8
84  7
236  61
Cryostat of ANG2
91  4
10  3
78  22
Cryostat of ANG3
105  5
84  5
927  46
Cryostat of ANG4
115  3
87  4
199  4
Cryostat of ANG5
100  4
26  4
1632  49
 16
 12
 110
measured by GeMPI*
* 127 kg
Monte Carlo simul.
Ch. Doerr,Uni HD
2002
surface
contamination
naked Ge-crystals deployed in liquid nitrogen or argon
(cooling medium and shield
against external radiation)
conventional detector
crystal gladding
one
out of
several
ten
reduction of contact and gladding material:
about factor 7000 in mass, 200 in surface
not enough space at LNGS for full shielding by liquid N2/Ar
GeMPI
material
LN2 shielding thickness
against 2.6 MeV for E-4**
activity [Bq/kg]
226
Ra (U)
228
Th (Th)
40
K
various
intrinsic
contamin.
/ (external)
 110
98 207Bi; 180 60Co
2.7x107 210Pb
 13 207Bi;  11 60Co
2.3x107 210Pb
 10 60Co
221 cm / (58.7 cm)
200
1800
17000 60Co
290 cm / (66.3 cm)
1200
7100
 3000
water*
1
0.04 - 0.008
2
liq. nitrogen
 0.3 (222Rn)
liq. argon
120 (222Rn)
concrete
8x106
lead (DowRun)
 29
 22
440
lead (Boliden)
 27
 26
460
copper (Lens)
 16
 12
steel (foil)
600
steel (Lens)
* BOREXINO
300
60
Co
12cm / (464 cm)
0.006 39Ar; 0.05 85Kr
1.1x106
1x107
215 cm / (41.0 cm)
39
Ar; 30 42Ar
(637 cm)
(396 cm)
9x107
**
backgroundindex at 2.039 MeV [counts/kg y keV]
GERDA
The GERmanium Detector Array for the search
of neutrinoless double beta decay of 76Ge
INFN LNGS, Assergi, Italy
INR, Moscow, Russia
A.Di Vacri, M. Junker, M. Laubenstein, C. Tomei, L. Pandola
I. Barabanov, L. Bezrukov, A. Gangapshev, V. Gurentsov, V.
Kusminov, E. Yanovich
JINR Dubna, Russia
S. Belogurov,V. Brudanin, V. Egorov, K. Gusev, S. Katulina,
A. Klimenko, O. Kochetov, I. Nemchenok, V.
Sandukovsky, A. Smolnikov, J. Yurkowski, S. Vasiliev,
ITEP Physics, Moscow, Russia
V.P. Bolotsky, E. Demidova, I.V. Kirpichnikov, A.A. Vasenko,
V.N. Kornoukhov
Kurchatov Institute, Moscow, Russia
MPIK, Heidelberg, Germany
C. Bauer, O. Chkvorets, W. Hampel, G. Heusser, W.
Hofmann, J. Kiko, K.T. Knöpfle, P. Peiffer, S. Schönert,
J. Schreiner, B. Schwingenheuer, H. Simgen, G. Zuzel
A.M. Bakalyarov, S.T. Belyaev, M.V. Chirchenko, G.Y.
Grigoriev, L.V. Inzhechik, V.I. Lebedev, A.V. Tikhomirov, S.V.
Zhukov
Univ. Köln, Germany
MPI Physik, München, Germany
J. Eberth, D. Weisshaar
Jagiellonian University, Krakow, Poland
M.Wojcik
Univ. di Milano Bicocca e INFN, Milano, Italy
E. Bellotti, C. Cattadori
71 physicists / 12 institutions / 4 countries
I. Abt, M. Altmann, C. Bűttner. A. Caldwell, R. Kotthaus, X.
Liu, H.-G. Moser, R.H. Richter
Univ. di Padova e INFN, Padova, Italy
A. Bettini, E. Farnea, C. Rossi Alvarez, C.A. Ur
Univ. Tübingen, Germany
M. Bauer, H. Clement, J. Jochum, S. Scholl, K. Rottler
Spokesperson: Stefan Schönert, MPIK Heidelberg
GERDA
The GERmanium Detector Array for the search
of neutrinoless double beta decay of 76Ge
10 cm Pb
stainless steel
1.5 m
radioactivity
[Bq/kg]
Ø 3.8 m
instrumented
with PMT‘s as
cosmic veto
h ca 5 m
water shield
Ge
copper
concrete
 1x10-3
 20
8x106
Ra-226
 1x10-4
 26
1x107
Th-228

 1x10-2
88
Vespel or similar
2 x 10 cm Pb
Ø 4.0 m
Ø 9.4 m
9x107 K40
2.039 MeV
ANG2 LNGS, no shield
Heidelberg Moscow
plot from O. Chkvorets
also next
step for
screening at
nBq/kg level
envisioned level
for Gerda
exiting to see
what comes up
at this level
Acknowledgement:
MPI workshops (led by V. Mallinger, D. Doerflinger, P.Moegel)
M. Wojcik
E. Pernicka
H. Strecker
B. Freudiger
A. Piepke
M. Laubenstein
R. Davis
S. Schönert
R. Lackner
W. Hampel
G. Zuzel
M. Balata and his team
W. Rau
T. Kirsten
Y. Zakharov
my wife Lilo
J. Kiko
H. Simgen
B. Prokosch
Ch. Buck
H. Neder
H. V. Klapdor Kleingrothaus
LRT 2004 at SNO, Sudbury 12. December 2004
Comparison of
Radioassay techniques
for primordial U/Th decay chains and K
Ge-spectroscopy
suited for
 emitting nuclides
Rn emanation assay
226Ra, 228Th
Neutron activation
primordial parents
Liquid scintillation counting
 emitting nuclides
Mass spectrometry (ICP-MS; A-MS) primordial parents
Graphite furnace Atom Adsorption Sp.primordial parents
Roentgen Exitation Analysis
Alpha spectroscopy
primordial parents
210Po,
 emitting nuclides
difficult to compare since each method has its special application
Neutron activation analysis

n  41K  42 K 
42
12.36 h
Ca,
A. Piepke
 th  1.2 b (1.2 b)


22.3 m
27.0 d
n  232Th  233Th  233 Pa 233U ,


23.5 m
2.36 d
n  238U  239U  239 Np 239 Pu,
 th  6.1 b (7.8 b)
 th  2.3 b (7.9 b)
Sizable cross sections and long enough half lives
for delayed counting
NAA (TU Munich)
239Np
+
T1/2 = 193 ns
106 keV 
‘s + conv. electron
239Pu
 0.19 Bq/kg
 8x10-4 Bq/kg
 1x10-4 Bq/kg
Results of NAA study for some materials
Material
40K
PPO Lot 21-634
<8.8 •10-12
(3.2±1.1) •10-12
<2.7 •10-12
Evaporated PC+PPO
<73 •10-12
<1.5 •10-12
<2 •10-11
LS Sample 1
(5.3±0.7) •10-13
<15.8 •10-14
<5.1 •10-14
LS Sample 2
(3.1±0.6) •10-14
(1.8±0.6) •10-14
<1.3 •10-14
KamLAND Final LS
<2.4 •10-15 < 0.6 Bq/kg <5.5 •10<-150.02 Bq/kg <8 •10<-150.1 Bq/kg
[g/g]
232Th
A. Piepke
[g/g]
238U
[g/g]
For much more details on NAA look into
Z.Djurcic et. al., Nucl. Instr. And Meth. A 507 (2003) 680.
1000 tons of ultra clean LS was filled into KamLAND detector over 6
month period. KamLAND was ready to take data.
Gerdes, Univ. Frankfurt
limits of detection
238
U
235
U
234
U
236
U
239
Pu
240
Pu
241
Pu
242
Pu
241
-14
~ 5 x 10
-15
~ 5 x 10
-17
~ 10 x 10
-17
~ 3 x 10
-17
~ 3 x 10 g
-17
~ 3 x 10 g
-17
~ 3 x 10 g
-17
~ 3 x 10 g
Am ~ 3 x 10
90
Sr
232
Th
230
Th
g
g
g
g
< 1 nBq
< 1 nBq
~ 20 nBq
< 1 nBq
< 100 nBq
< 300 nBq
~ 130 µBq
< 1 µBq
-17
g ~ 5 µBq
-15
g ~ 5 mBq
~ 1 x 10
-14
~ 3 x 10 g ~ 1 nBq
~ 3 x 10-17 g ~ 20 nBq
method
Ge-spectroscopy*
suited for
sensitivity for U/Th
 emitting nuclides
10-100 Bq/kg
Rn emanation assay
226Ra, 228Th
0.1-10 Bq/kg
Neutron activation
primordial parents
0. 01 Bq/kg
Liquid scintillation counting
 emitting nuclides
1 mBq/kg
Mass spectrometry (ICP-MS; A-MS) primordial parents
1-100 Bq/kg
Graphite furnace Atom Adsorption Sp.primordial parents
1-1000 Bq/kg
Roentgen Exitation Analysis
primordial parents
10 mBq/kg
Alpha spectroscopy
210Po,
1 mBq/kg
 emitting nuclides
* Needs counting time of several weeks to several month
Best see Borexino Collaboration, Arpesella, C. et al.,
Measurements of extremely low radioactivity levels in
Borexino, Astrop. Phys. 18 (2002) 1-25