Kinematic searches Relativity Uncertainty Best candidate: Using molecular tritium, daughter will be 12.06.2014 Kai Zuber 25
Tritium beta decay Half-life :12.3 years Matrix element: 5.55 Endpoint energy: about 18.590 kev 12.06.2014 Kai Zuber 26
Kurie plot 12.06.2014 Kai Zuber 27
First measurements How to measure? 12.06.2014 Kai Zuber 28
Electrostatic spectrometer 12.06.2014 Kai Zuber 29
More experiments 1972 Bergkvist m<55 ev 1980 Lubimov m= 35 ev!!! 1980-1990 Livermore, Los Alamos, Zurich,... 1990-200x Troitzk, Mainz m <2.35 ev Before about 1995: Always negative m 2 far away from zero, some systematic effects were not understood 12.06.2014 Kai Zuber 30
Tritium beta decay 12.06.2014 Kai Zuber 31
Mainz experiment C. Kraus et al., Eur. Phys. J. C 40 (2005) 12.06.2014 Kai Zuber 32
MAC-E Filter spectrometer (Mainz, Troitzk, KATRIN) Magnetic Adiabatic Collimation combined with an Electrostatic filter L = constant of motion 12.06.2014 Kai Zuber 33
KATRIN The next generation (ultimate spectrometer?): Aimed sensitivity of 0.2 ev 12.06.2014 Kai Zuber 34
KATRIN- The next step
Take the long way home...
Alternative ways??? Fraction of events in endpoint region E scales with (Q-E) 3, lower endpoints? Q=2.47 kev Use of cryo-bolometers MARE project, stopped due to experimental limitations 12.06.2014 Kai Zuber 37
Alternative ways? Excited state transitions? C.M. Cattadori et al., NPA 748 (2005) Combined with Penning trap measurement : Endpoint of 155 ± 24 ev Endpoint of 350 ± 150 ev B.J. Mount et al., PRL 103 (2009) J.S.E. Wieslander et al., PRL 103 (2009) 12.06.2014 Kai Zuber 38
Project 8 B. Monreal, J. Formaggio, PRD 80 (2009) Cyclotron frequency of relativistic particles Emission of microwaves to be detected by antenna array 12.06.2014 Kai Zuber 39
Electron capture (EC) and neutrino mass Measures the neutrino mass (not anti-neutrino mass like beta decay) Radiative EC, internal bremsstrahlung - De-excitation spectrum depends on neutrino mass - Calorimetric measurement 12.06.2014 Kai Zuber 40
The case of Ho-163 Endpoint of internal bremsstrahlungs spectrum Current bound : m < 225 ev P.F. Springer et al., Phys. Rev. A 35 (1987) 12.06.2014 Kai Zuber 41
EC signal Very low Q-value allows only M-capture and higher shells Again, precision mass measurement is neccesssary 12.06.2014 Kai Zuber 42
Ho-163 measurement Use cryodetectors 12.06.2014 Kai Zuber 43
Holmes and ECHO ECHO HOLMES HOLMES ECHO 12.06.2014 Kai Zuber 44
Kinks in beta decay 12.06.2014 Kai Zuber 45
The famous 17 kev neutrino (around 1990) Tritium Sulphur-35 Finally ruled out (almost as much positive than negative observations) 12.06.2014 Kai Zuber 46
Double beta decay (A,Z) (A,Z+2) +2 e - + 2ν e (A,Z) (A,Z+2) + 2 e - - 2νββ 0νββ 2 requirements: - Neutrinos are Majorana particles - Neutrinos must have a non-vanishing rest mass (helicity) The smaller the neutrino mass the longer the half-life
Requirements - I 1.) m(a,z) > m(a,z+2) 2.) Single beta decay must be forbidden (m (A,Z) < m (A,Z+1)) or at least strongly suppressed (large change in angular momentum)
Example: Ge-76 There are only 35 isotopes in nature for double electron emission 12.06.2014 Kai Zuber 49
Signal information (A,Z) (A,Z+2) ++ + 2 e - - Signal: One new isotope (ionised), two electrons (fixed total energy) - Single electron energies - Angle between electrons - Sum energy of both electrons - Daughter ion (A,Z+2) - Gamma rays (eg. four 511 kev photons in β + β + or excited state transitions)
2νββ All even-even ground state transitions are 0 + 0 + - (A,Z) (A,Z+2) +2 e - + 2ν e Fermi s Golden rule: Single electron spectrum dλ = 2πδ(E 0 E f ) f m,β < f H β m >< m H β i > E i E m p ν E e 2 Angular distribution with β = p/e Sum energy spectrum: dn de E(Q E)5 (1+ 2E + 4E 2 3 + E 3 3 + E 4 30 ) 12.06.2014 Kai Zuber 51
0νββ Any L=2 process can contribute to 0νββ R p violating SUSY V+A interactions Extra dimensions (KK- states) Leptoquarks Double charged Higgs bosons Compositeness Heavy Majorana neutrino exchange Light Majorana neutrino exchange... Nice interplay with LHC 1 / T 1/2 = PS * NME 2 *ε 2
Light Majorana neutrinos 2 m ν = U ei m ν i = c 12 i ε m ν = 2 U ei m ν i i 2 c 13 2 m 1 + s 12 2 c 13 2 e iα 1 m + s 2 2 13e iα 2 m 3 1 / T 1/2 = PS * NME 2 * (<m ν > / m e ) 2 Schechter and Valle 1982: Independent of mechanism for neutrinoless DBD Majorana neutrino mass will appear in higher order! Actual calculation: M. Duerr, M. Lindner, A. Merle, JHEP 1106,091 (2011)
Spectral shapes 0νββ: Peak at Q-value of nuclear transition Measured quantity: Half-life Dependencies (BG limited) T 1/2 a ε (M t/δe B) 1/2 link to neutrino mass 1 / T 1/2 = PS * ME 2 * (m ν / m e ) 2 Sum energy spectrum of both electrons
Perfect world experiment No background δ function as peak 100 % abundance 100% detection efficiency Infinite measuring time Infinite mass T 1 1/ 2 aε Mt ΔEB Life is easy, the rest is just details 12.06.2014 Kai Zuber 55
Back of an envelope This is the 50 mev option, just add 0 s to moles and kgs if you want smaller neutrino masses Τ 1/2 = ln2 a N A M t / N ββ (τ>>t) ( Background free) For half-life measurements of 10 26-27 yrs 1 event/yr you need 10 26-27 source atoms This is about 1000 moles of isotope, implying about 100 kg Now you only can loose: nat. abundance, efficiency, background,...
Experimental approaches There is no super-isotope! 11 isotopes of interest Isotope AME 2003 Q- values 2012 Ca- 48 4272 ± 4 4262.96 ± 0.84 Ge- 76 2039.006 ±0.050 2039.006 ± 0.050 Se- 82 2995.5 ± 1.9 2997.9 ± 0.3 Zr- 96 3347.7 ±2.2 3347.7 ± 2.2 Mo- 100 3035 ±6 3034.40 ± 0.17 Pd- 110 2004 ±11 2017.85± 0.64 Cd- 116 2809 ± 4 2813.50 ± 0.13 Sn- 124 2287.8±1.5 2292.64 ± 0.39 Te- 130 2530.3 ±2.0 2527.518± 0.013 Xe- 136 2462 ±7 2457.83± 0.37 Nd- 150 3367.7 ±2.2 3371.38 ± 0.20 Candles GERDA, Majorana SuperNEMO, LUCIFER MOON, AMore COBRA Tin.Tin CUORE, SNO+ EXO, KamLAND-Zen, NEXT, XMASS MCT
Mass hierarchies and DBD 76 Ge T 1/2 = 1.19 x 10 25 yr 1 Claim of evidence 10 25 yrs 10 26 yrs 2 10 27 yrs H.V. Klapdor-Kleingrothaus et al. Phys. Lett. B 586, 198 (2004) 10 28 yrs 3 normal inverted 1.) Is the claimed evidence correct? GERDA phase I 2.) Can we probe the inverted hierarchy? 3.) What about the normal hierarchy?
Heidelberg Moscow Experiment Isotope of interest: 76Ge Still only 1 decay per year per 10 kg Ge Background obtained 0.1 count/kev/kg/yr
Ge-spectrum 0ν peak region 12.06.2014 Kai Zuber 60
Evidence? 2001 2004 200 6 H.V. Klapdor-Kleingrothaus et al., Phys. Lett. B 586, 198 (2004) Mod.Phys.Lett.A21:1547-1566 (2006) Very controversial discussion in the community H.V. Klapdor-Kleingrothaus et al., Eur.Phys.J. A12 (2001) 147-154
KamLAND - Zen Using 400 kg of Xe (91.7% enriched in Xe-136) T 1/2 > 1.9 x 10 25 years (90%CL) A. Gando, PRL 111, 062502 (2013) Data taking after purification started Dec. 2013, 110m Ag down by more than an order of magnitude K. Zuber