Schematic drawing of scintillator system

GERDA-Principal Setup

Idea : Running bare Ge crystals in LAr

9

GERDA opened window in June collaboration meeting

Phase I data taking

66

Phase I data taking

16.7.2013

Background model (flat background in region of 200 keV

around signal after removing lines)

Phase I results

Pulse shape discrimination: M. Agostini et al. Eur. Phys. J. C 71,2583 (2013)

Result Phase 1: M. Agostini et al., PRL 111, 122503 (2013)

200 kg of enriched (80%) Xe-136 at hand

EXO-200

Future option: Barium tagging

First observation of 2nu decay of Xe-136, N. Ackerman et al., PRL 107, 212501 (2011)

Current half-life limit on 0nu decay : T1/2 > 1.1 x 1025 years (90%CL) J. B. Albert et al., doi:10.1038/nature13432 (2014)

In conflict with positive claim for almost all matrix element calculations

Uncertainties due to conversion

General dependence Current data

Mass hierarchies and DBD

With the known oscillation results everything is fixed

M. Lindner, A.. Merle, W. Rodejohann, Phys. Rev. D 73, 053005 (2006)

excl

uded

excluded

Near term goal: Touching the IH

Kai Zuber 70

A.  Dueck, W. Rodejohann, K. Zuber, PRD 83, 113010 (2011)

€

T1/ 2( )−1 ∝ gA4

r02

The lower end of the IH

Kai Zuber 71

A better measurement of Θ12 is desirable (JUNO) a factor 2 in mass implies a factor 16 imrovement in the half-life!

A. Dueck, W. Rodejohann, K. Zuber, PRD 83, 113010 (2011)

COBRA

Use large amount of CdZnTe Semiconductor Detectors

Large array of CdZnTe detectors

K. Zuber, Phys. Lett. B 519,1 (2001)

Advantages

 Q-value at 2813 keV, above all major gamma lines from natural chains

 Room temperature  Semiconductor (clean)  Good energy resolution  Enrichment (>90%)

feasible and purification as well

 Coincidences  Pulse shape analysis  Very modular design  Tracking option

S. Pirro, Milano

Coplanar grid (CPG) technology

 Realisation of a Frisch grid in a semiconductor (P. Luke, LBNL)

  Interaction depth z and energy E can be determined from CA and NCA signals (Shockley – Ramo theorem)

M. Fritts et al., NIM A 708,1 (2013)

Lateral surface events

Distortion of pulses at lateral surfaces

M. Fritts et al., NIM A 749, 27 (2014)

CA side

NCA side

Central

Interaction depth vs. energy

Background in ROI is about 1 count/keV/kg/yr Without z=0.8 region about 0.3 counts/keV/kg/yr

Based on layers 1-2 (82.3 kg*days)

King COBRA experiment

Kai Zuber 77

  Amount of material tuned to touch IH, strong modular design   Moving to 6x larger detectors

Modules, ladders, layers and towers

CdTe - pixel detectors

55 µm pitch Timepix detectors

SNO+

 Advantage: Loading of a large amount of isotope  Using the SNO infrastructure, detector is Te-loaded scintillator  Major changes : rope system , LSc purification plant, DAQ

Kai Zuber 80

Scintillator loading

Kai Zuber 81

Proposed start: Next year

Sensitivity

0νββ

Could be more contributions....

If peak is ever observed 0νββ, the real work begins Cartoon: Contributions

Neutrino mass

Rp violating SUSY

Right handed weak currents

Master equation

1 / T1/2 = PS * NME2 * (<mν> / me)2

Measurement Exact calculation

Complex calculations

Quantity of interest

Nuclear Physics

J. Kotila, F. Iachello, PRC 85, 034316 (2012) S. Stoica, M. Mirea, PRC 88,037303 (2013)

Severe nuclear structure issue

Phase space factors (new vs. old)

25.04.2013 Kai Zuber 84

2νββ

NME – Intermediate states

€

2νββ

€

0νββ

NME – Intermediate states

Charge exchange measurements at KVI and RCNP

Differential cross section in forward direction directly linked to Gamow-Teller strength

Rescaled as people use different gA (1-1.25) and R0 (1.0-1.3 fm)

Matrix element

Several new techniques applied in last years

would do it

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4 ± 4

Alternative modes

Best candidate : 152Gd measured with SHIPTRAP at GSI

S. Eliseev et al., Phys. Rev. Lett. 106,052504 (2011)

Resonant enhancement (*106) of 0nu ECEC if excited state in daughter is degenerate (within 200 eV) with initial ground state (-> Q-values)

•  (A,Z) → (A,Z-2) + 2 e+ (+2νe) β+β+

•  e- + (A,Z) → (A,Z-2) + e+ (+2νe ) β+/EC

•  2 e- + (A,Z) → (A,Z-2) (+2νe) EC/EC

Q-4mec2 Q-2mec2 Q

Enhanced if V+A is at work

J. Bernabeu, A. deRujula, C. Jarlskog, Nucl. Phys. B 221,15 (1983) S. Zujkoswski, S. Wycech, PRC 70, 052501 (2004)

M. Hirsch et al, Z. Phys. A 347,151 (1994)

Cosmological mass bounds

Kai Zuber 89

  If big bang theory is correct there should be a CνB   Properties can be linked to CMB

 To close the universe

Major act of massive, light neutrinos: Washing out structures on small scales, acts as hot dark matter

€

nν =6ς (3)11π 2 TCMB

3 ≈112cm−3

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Ων h2 =

mν ,tot

94eV

Cosmological mass bounds

Kai Zuber 90

  Planck data fix almost all other cosmological parameters

Effect of mν > 0

Neutrino masses and cosmology There is a 1.95 K relic neutrino background... Still to be detected....

Large scale structure

Kai Zuber 92

Large scale structure

Kai Zuber 93

Linear theory

Non linear theory

9.6

S. Hannestad et al.

Neutrino masses

Kai Zuber 94

Values depend crucially on data sets used, analysis and assumptions (always model dependent)

Personally I think an upper limit of about 1 eV is probably safe

More than 3 neutrinos?

Kai Zuber 95

Beta decay:

Double beta decay:

Cosmology:

+ oscillation parameters

€

Ων h2

Kind of summary

Conclusion

Neutrino physics has made major progress over the last 15-20 years in establishing a non-zero rest mass

Determination of absolute mass essential as this would fix all the oscillation results

Neutrino mass bounds from cosmology , beta decay and double beta decay are all around the 1 eV scale (or slightly below)

Recently several next generation double beta experiments have started (Candles, GERDA, KamLAND-Zen, EXO) First exciting results from Xe-experiments and GERDA disfavour claim of evidence

  New projects are on the horizon or close to start data taking

 Given the difficulty still new ideas/approaches are invented   Very exciting field of physics

“Nobody said it would be easy and nobody was right!'" —George W. Bush