1. Gamma spectrometry in deep sea water
Jose Busto
CPPM /

3. Anthropogenic Radionuclides
Concentrations of Natural Radionuclides in the sea
Radionuclide Half – life Activity ( dpm / l)
40 K yr
87Rb yr
129I yr
238U yr ~3 – 0.2
… ,226Ra, 214Bi, 210Pb … 206Pb
232Th yr
..., 228Ac,212Pb, 208Tl … 208Pb
3H yr
7Be d
14C yr
137Cs, 60Co, 90 Sr, 3H, ….
Single Long
Lived
U and Th
Chains
Cosmogenic
Anthropogenic Radionuclides

4. Radioactivity in the marine environment
 1950’s
-> Water or sea floor measurements
=> mineral exploration
=> geological mapping
=> sediments transport
=> discharge and dump of radioactive wastes
=> radiation damage to optical fiber telephone cables.
=> …

5. + - Single sample collection of water or sediments
===> Classical Radioanalytical methods
Preconcentration
Separation
Long-term measurements
Alpha spectrometry
Gamma spectrometry
Neutron Activation Analysis
Mass spectrometry +
Access to all radionuclide with very high sensibility
( -> < g/g in 238U ) -
No continuous evaluation of radioactivity

6. Towed detector systems
Mapping large area
Control time of measurement
Gamma spectrometry (NaI)

7. Autonomous in situ detectors
Very high statistic time
Evolution of radioactivity
Gamma spectrometry (NaI, Ge)

8. Measure the radioactivity of the water continuously in the ANTARES site
The case of 40K
40Ca + e- + ne
40Ar + b-
(89.3 %)
40K --->
e+ + ne ne b+
(0.03 %) EC
(10.67 %)
(10.7 %)
g spectrometry
(NaI, Ge)
(89.3 %)
40K
Cerenkov light
(ANTARES)
10.67 % EC
1460 keV
1312 keV b-
40Ca
40Ar

9. 13.0 ± 0.5 Hz observed => 12 ± 4 Hz expected
40K continuous measurement with ANTARES
-2400 m
13.0 ± 0.5 Hz observed => 12 ± 4 Hz expected
40Ca
40K
Cerenkov
Anti-neutrino b-

10. Project to measure gamma activity in ANTARES site
NaI g spectrometer in an standard ANTARES glass sphere
USB feed
HV + MCA
3’ x 3’ NaI cristal
17’ ANTARES glass sphere
3’ PM
FIT PC2 data acquisition ( 6W )

11. 226Ra spectrum
226Ra
214Pb
214Pb
214Pb
214Bi
214Bi
214Bi

12. 40K spectrum
226Ra
214Pb
40 K
214Bi

13. Preliminary tests => Autonomy ~ 15 days
 Autonomy increase => suppression of hard disk
Still to do
 inner background => Pb shielding (LSM)
 efficiency => MC v.s KCl dilute in water

14. A dream ?
Gamma spectrometry with Ge detectors
226Ra Ge spectrum

15. Not a dream Canberra 4 h operation with a single battery
Existing project in India cost for a continuous Ge 500 m deep

16. Conclusion Many measurements of sea radioactivity.
Long period in situ measurements never done (?).
 Installation of a preliminary continuous NaI gamma
spectrometer in the ANTARES site.
Possibility to perform continuous gamma spectrometry
with very high energy resolution ( Ge ).

18. Radioactivity from Salt
 Fraud control