Low Counting Experimental Techniques nd 2 lecture: sources of radioactive background Fedor Danevich Institute for Nuclear Research, Kyiv, Ukraine http://lpd.kinr.kiev.ua [email protected] [email protected] 1 F.A. Danevich Univ. Tor Vergata November 11, 2015 • Brief summary of the 1st lecture Effects beyond the Standard Model neutrino oscillations massive neutrino Expected without oscillations Experiment Takaaki Kajita upward downward Super-Kamiokande Observation of solar neutrino neutral current interaction: 3 e,, + d n + p, n + d H + e n U Arthur B. McDonald Neutrino is massive lL lj jL j1 SNO Many questions on properties of neutrino and weak interaction remains open 2 • Brief summary of the 1st lecture Effects beyond the Standard Model dark matter, dark energy • Galactic rotation curves • Velocity dispersions of galaxies • Structure formation The Milky Way rotation curve • Direct observations The Bullet cluster 1E 0657-56 The Cosmic Microwave Background Galaxy Cluster Abell 1689 temperature fluctuations • Age of star clusters and the data of nuclear chronology • The today’s large structure of the Universe • Direct observations of galaxies accelerated motion 95% of what makes up the Universe is still a mystery for science 3 F.A. Danevich Univ. Tor Vergata November 11, 2015 • Brief summary of the 1st lecture Investigation of neutrino and weak interaction neutrinoless double beta decay 2EC, EC+, 2+ 2 Double decay was considered for the first time by Maria Goeppert–Mayer [1] • The 02 decay is only possible if neutrino is Paul Adrien Maurice massive Majorana particle and the Lepton number is Dirac 1902-1984 broken Ettore Majorana 1906 – 1959 (?) 4 F.A. Danevich Univ. Tor Vergata November 11, 2015 • Brief summary of the 1st lecture Search for hypothetical processes and particles In fundamental physics, if something can be tested, it should be tested [1] • nucleon decay • Pauli principle breaking • magnetic monopols • electric charge non-conservation • extra dimensions • axions • sterile neutrino L.B. Okun, Note on testing charge conservation and the Pauli exclusion principle, Phys. Rev. D (1992) 45, VI.10. 5 F.A. Danevich Univ. Tor Vergata November 11, 2015 • Brief summary of the 1st lecture Investigation of rare decays rare and decays, rare nuclear reactions 209 Ge-NTD Longest decay of Bi Germanium neutron transmutation doped thermistors investigate nuclear reactions with the formation of 115 decay of In with lowest Q light isotopes such as 2H, 3He, 4He, 6Li, and 7Li 6 F.A. Danevich Univ. Tor Vergata November 11, 2015 in this lecture: • Natural radioactivity • Cosmic rays • Neutrons • Cosmogenic and neutron induced radioactivity • Anthropogenic radioactivity • Noise, pile-up 7 F.A. Danevich Univ. Tor Vergata November 11, 2015 Radioactivity There are several types of radioactive decay, in many cases a combination of a few modes occurs • Gamma emission, electron conversion • β- decay n delayed neutron emission • β+ decay 2n delayed 2-neutron emission + + • Electron Capture (EC) p delayed proton emission + 2p + delayed 2-proton emission • β-delayed particle emission delayed emission • Neutron decay + + delayed emission • Double β decay d delayed deuteron emission • Proton decay t delayed triton emission +SF + delayed fission • Alpha decay SF delayed fission • Cluster decay • Spontaneous Fission (SF) 2 double decay EC/EC double electron capture EC+ electron capture with + emission + + 2 double decay 8 F.A. Danevich Univ. Tor Vergata November 11, 2015 Natural radioactivity There are plenty of natural primordial radioactive elements K, Ca, V, Ge, Se, Ru, Ze, Mo, Cd, In, Te, Xe, La, Nd, Eu, Sm, Gd, Lu, Hf, W, Rh, Os, Pt, Bi, Th, U • Gamma emission, electron conversion • β- decay • β+ decay • Electron Capture (EC) • Double β decay 2 double decay • Alpha decay • Spontaneous Fission (SF) 9 F.A. Danevich Univ. Tor Vergata November 11, 2015 10 Ф.А.ДаневичF.A. Danevich Хімічний факультет КНУ ім. Т.ШевченкаUniv. Tor Vergata 6 грудня 2013 November 11, 2015 11 Ф.А.ДаневичF.A. Danevich Хімічний факультет КНУ ім. Т.ШевченкаUniv. Tor Vergata 6 грудня 2013 November 11, 2015 12 Ф.А.ДаневичF.A. Danevich Хімічний факультет КНУ ім. Т.ШевченкаUniv. Tor Vergata 6 грудня 2013 November 11, 2015 13 Ф.А.ДаневичF.A. Danevich Хімічний факультет КНУ ім. Т.ШевченкаUniv. Tor Vergata 6 грудня 2013 November 11, 2015 14 Ф.А.ДаневичF.A. Danevich Хімічний факультет КНУ ім. Т.ШевченкаUniv. Tor Vergata 6 грудня 2013 November 11, 2015 Natural elements containing radioactive isotopes Element Radioactive Isotopic Half-life (yr) Activity in Mass of element isotope, abundance 1 g of (g) corresponding decay (%) element (Bq) to activity of a modes radioactive isotope 1 mBq/kg Potassium 40K, , 0.0117(1) 1.248(3) 109 31.0 3.22 10-8 Calcium 48Ca, 2 0.187(21) 4.4 1019 1.17 10-8 85 Vanadium 50V 0.250(4) 1.4(4) 1017 4.7 10-6 0.21 Germanium 76Ge, 2 7.83(7) 1.5(1) 1021 9.1 10-9 110 Selenium 82Se, 2 8.73(22) 9.2(7) 1019 1.53 10-7 6.5 Rubidium 87Rb, 27.83(2) 4.81(9) 1010 881 1.14 10-9 Zirconium 96Zr, 2 2.80(9) 2.3(2) 1019 1.68 10-7 6.0 Molybdenum 100Mo, 2 9.67(20) 7.1(4) 1018 1.80 10-6 0.55 Cadmium 113Cd, 12.22(12) 8.04(5) 1015 1.78 10-3 5.62 10-4 116Cd, 2 7.49(18) 2.8(2) 1019 3.05 10-7 3.28 Indium 115In, 95.71(5) 4.41(25) 1014 0.250 4.0 10-6 Tellurium 128Te, 2 31.74(8) 2.0(3) 1024 1.6 10-11 62 000 130Te, 2 34.08(62) 6.8(1.2) 1020 5.1 10-8 20 Lanthanum 138La, , 0.090(1) 1.02(1) 1011 0.846 1.182 10-6 Neodymium 144Nd, 23.8(3) 2.29(16) 1015 9.6 10-3 1.05 10-4 150Nd, 2 5.6(2) 8.2(9) 1018 6.0 10-7 1.66 15 F.A. Danevich Univ. Tor Vergata November 11, 2015 Natural elements containing radioactive isotopes Element Radioactive Isotopic Half-life (yr) Activity in Mass of element isotope, abundance 1 g of (g) corresponding decay (%) element (Bq) to activity of a modes radioactive isotope 1 mBq/kg Samarium 147Sm, 14.99(18) 1.06(2) 1011 127 7.85 10-9 148Sm, 11.24(10) 7(3) 1015 1.4 10-3 7 10-6 Gadolinium 152Gd, 0.20(1) 1.08(8) 1014 1.61 10-3 6.2 10-4 Lutetium 176Lu, 2.59(2) 3.78(7) 1010 51.5 1.94 10-8 Hafnium 174Hf, 0.16(1) 2.0(4) 1015 6.08 10-5 0.016 Tungsten 180W, 0.12(1) 1.8(2) 1018 4.9 10-8 20 Rhenium 187Re, 62.60(2) 4.12(11) 1010 1075 9.3 10-10 Osmium 186Os, 1.59(3) 2.0(11) 1015 6 10-4 0.0018 Platinum 190Pt, 0.014(1) 6.5(3) 1011 0.0150 6.7 10-5 Bismuth 209Bi, 100 1.9(2) 1019 3.3 10-6 0.30 Radium 226Ra, 100 1600(7) 3.6581010 2.734 10-17 Thorium 232Th, 100 1.40(1) 1010 4 070 2.456 10-10 Uranium 234U, 0.0054(5) 2.455(6) 105 12400 8.0 10-11 235U, 0.7204(6) 7.04(1) 108 575.9 1.736 10-9 238U, , 2 99.2742(10) 4.468(3) 109 12 346 8.100 10-11 16 F.A. Danevich Univ. Tor Vergata November 11, 2015 Background spectrum of HPGe detector 2615 keV 208Tl (232Th) the most energetic natural gamma line The most valuable gamma quanta come from 40K and daughters of 232Th, 238U Gerd Heusser, Annu. Rev. Nucl. Part. Sci. 45 (1995) 543 17 F.A. Danevich Univ. Tor Vergata November 11, 2015 The most valuable natural radioactive elements are K, Th, U Concentration in the Earth’s crust: K: (15-26) 103 ppm Th: 6-10 ppm U: 2-3 ppm 1 Bq / kg 238U = 80 10-9 g/g of U (80 ppb U) 1 Bq / kg 232Th = 246 10-9 g/g of Th (246 ppb Th) 1 Bq / kg 40K = 31 10-6 g/g of K (31 ppm K) 18 F.A. Danevich Univ. Tor Vergata October 12, 2015 Radioactive decay chains (families) Nuclei heavier than A = 208 are unstable, mainly relatively to alpha decay due to increase of Coulomb interaction. The nuclei belong to four decay chains beginning from 232Th, 235U, 238U, 237Np Chain Atomic number Isotopic Half-life concentration 232Th … … 208Pb 4n 100% 1.40(1)1010 yr 238U … …. 206Pb 4n + 2 99.2742% 4.468(3)109 yr 235U (239Pu *) … …. 207Pb 4n + 3 00.7204% 7.04(1)108 yr 237Np … …. 205Tl ** 4n + 1 2.144(7)106 yr 239 4 * T1/2( Pu) =2.411(3) 10 yr ** The family decayed almost completely 19 mass spectro- 238 U decay chain metry gamma active nuclides = 99.3 % sub chains highly volatile if Rn can escape, (plate out activity) also from otherwise Rn and atmospheric Ra included deposition G.Housser 20 Rn and its progenies 116 CdWO4 crystal scintillator in the DAMA Crys at Gran Sasso Lab 21 Rn in Borexino 210Po (daughter of 210Pb) appear in Borexino as result of Radon penetration / emanation 22 232 Th decay chain mass spectrometry gamma active nuclides = 100 % sub chain if Rn can escape, (plate out activity) otherwise Rn and the progenitors up to 228Th included G.Housser 23 Secular equilibrium Activities of all isotopes of the chain in a sample of material without substantial physical or chemical influence are equal if the age of the sample exceeds several half- lives of the most long living daughter with different chemical properties than that the parent nuclide of the chain Broken equilibrium Activities of daughter isotopes in a sample of material can be rather different during a few T1/2 if they were subjected to physical or chemical transformations (if the isotopes are isotopes of different elements) Broken equilibrium inside decay chains is a typical situation for the most of materials produced by industry In natural samples all the isotopes of U/Th families are mainly in equilibrium If not to say about Radon and its progenies… Rn Rn Rn Rn Rn 24 F.A.