# Presentation: 237129

## From CUORICINO to CUORE: 

**To probe the inverted hierarchy region**

**On behalf of the CUORE collaboration**
**  ****Adapted from Andrea Giuliani’s TAUP presentation**
**            ****Sendai Japan, September 11-15, 2007 **

-                       Frank Avignone
-                University of South Carolina
-                                and
-       INFN Laboratori Nazionali del Gran Sasso

## The CUORE collaboration

**The CUORE collaboration**

## Outline 

-  130Te bolometers

-   Structure of CUORICINO, present results

-   From CUORICINO to CUORE

-   The background: model, investigation and solution

**Outline**** **

-   CUORICINO/CUORE potential according to recent
-      nuclear structure calculations

-   Conclusions

## Decay modes for Double Beta Decay

## Electron sum energy spectra in DBD

- The shape of the two electron sum energy spectrum enables us to distinguish between the two decay modes

## Experimental approaches to direct searches

- Two approaches for the detection of the two electrons:

## Outline 

-  130Te bolometers

-   Structure of CUORICINO, present results

-   From CUORICINO to CUORE

-   The background: model, investigation and solution

**Outline **

-   CUORICINO and CUORE potential according
-     to recent nuclear calculations

-   Conclusions

##                130Te as a DBD candidate

-   high natural isotopic abundance (nat. abundance = 33.87 %)
-   high transition energy ( Q = 2530 keV )
-   encouraging theoretical matrix element
-   observed with geo-chemical techniques
-      (incl = ( 0.7 - 2.7 )  1021 y)
-   2 DBD decay observed by a precursor bolometric experiment (MIBETA)
-      and by NEMO-3 at the level = (7.6 )  1020 y

- Large natural abundance
-  Low-cost
-  Expandability of Double-Beta Decay experiments

## The bolometric technique for 130Te: detector concepts

## Tellurium oxide bolometers for DBD

## Outline 

-  130Te and bolometers

-   Structure of CUORICINO and present results

-   From CUORICINO to CUORE

-   The background: model, investigation and solution

**Outline **

-   CUORICINO and CUORE potential according to recent nuclear calculations

-   Conclusions

## CUORICINO/CUORE Location

**CUORICINO/CUORE Location**

**    ****CUORICINO ****experiment installed in **
**Laboratori Nazionali del Gran Sasso**
**L'Aquila – ITALY**
**the mountain provides a ****3500 m.w.e. shield**** against cosmic rays**

- CUORE
-  (hall A)

- CUORICINO
- (hall A)

## The CUORICINO structure

-                      11 modules x 4 detector (790 g) each
- 	         2 modules x 9 detector (340 g) each
-                       M = ~ 41 kg   ~ 5 x 1025 130Te nuclei

**The CUORICINO structure**

##  Detector performance

** ****Detector performance**

- 2.6

- 1.6

- 0.6

- Energy [MeV]

- Counts (/1.2 keV)

- 10

- 60

- 238U + 232Th calibration spectrum

- 208Tl

- 214Bi

- 40K

- 228Ac

- Performance of CUORICINO detectors (555 cm3 - 790 g):
-   Detector base temperature: ~ 7 mK
-   Detector operation temperature: ~ 9 mK
-   Detector response:   ~ 250 V/ MeV
-   FWHM resolution: ~ 3.9 keV @ 2.6 MeV

## CUORICINO results

- 130Te
- 0

- 60Co sum peak
- 2505 keV
- ~ 3 FWHM from
- DBD Q-value

**********/2****0******** ****(y) > 3.0 ******** 10****24**** y  ****(90%  CL )**

- M < 0.38 – 0.58 eV

**CUORICINO results**

**MT = 11.83 kg ****130****Te ******** y**

**Bkg** = 0.18±0.02 c/keV/kg/y

* **Rodin et al. nucl-th/0706.4304*
*Caurier et al., New Shell Model*

- Average FWHM resolution
-  for 790 g detectors: 7 keV

## Outline 

-  130Te and bolometers

-   Structure of CUORICINO and present results

-   From CUORICINO to CUORE

-   The background: model, investigation and solution

**Outline**** **

-   CUORICINO/CUORE potential according to recent nuclear calculations

-   Conclusions

## From CUORICINO to CUORE(Cryogenic Underground Observatory for Rare Events)

**From CUORICINO to CUORE****(****C****ryogenic ****U****nderground ****O****bservatory for ****R****are ****E****vents****)**

- and granularity

## CUORE funding and schedule

-  CUORE has a dedicated site in LNGS and the construction of site started

-  The CUORE refrigerator is fully funded and has been ordered

-  1000 crystals: promised funding by INFN and US DOE

-  The CUORE Electronics will be funded by the NSF via USC

**First CUORE tower “CUORE-0" assembled in ****2008**
**and operated in ****2009**** in CUORICINO Cryostat **
**CUORE scheduled to begin in January ****2011**

## CUORE sensitivity

## CUORE and the inverted hierarchy region

**Quasi-degenarate**

*S. Pascoli, S.T. Petcov*

**Inverted hierarchy**

**Normal hierarchy**

- M

- Lightest neutrino mass

## Outline 

-  130Te and bolometers

-   Structure of CUORICINO and present results

-   From CUORICINO to CUORE

-   The background: model, investigation and solution

**Outline **

-   CUORICINO and CUORE potential according to recent nuclear calculations

-   Conclusions

## The CUORE background model

-  Sources of the background

- Radioactive contamination in the detector materials (bulk and surface)
- Radioactive contamination in the set-up, shielding included
- Neutrons from rock radioactivity
- Muon-induced neutrons

## The CUORE background components

- Component

- Background in DBD region
- ( 10-3 counts/keV kg y )

- Environmental gamma

- Apparatus gamma

- Crystal bulk

- Crystal surfaces

- Close-to-det. material bulk

- Close-to-det. material surface

- Neutrons

- Muons

- < 1

- < 1

- < 0.1

- < 3

- < 1

- ~ 20 – 40

- ~ 0.01

- ~ 0.01

**The only limiting factor **

## The CUORICINO background and the surface radioactivity model

**Gamma region**

## Reconstruction of the CUORICINO spectrum 

**in the region 2.5 – 6.5 MeV **

**0********DBD**

## The additional component: 

**inert material surface contamination **

- In order to explain the 2.0 - 4 MeV region BKG, one has to introduce
- 238U or 210Pb surface contamination of the copper structure facing the detectors

## Strategies to control surface background 

-    Mechanical action
-    Chemical etching / electrolitic processes
-    Surface passivation

**Strategies to control surface background **

## Outline 

-  130Te and bolometers

-   Structure of CUORICINO and present results

-   From CUORICINO to CUORE

-   The background: model, investigation and solution

**Outline**** **

-   CUORICINO and CUORE potential according to recent nuclear calculations

-   Conclusions

## CUORICINO and the KKDK claim of evidence

**T****1/2****0v **(y)** = (0.69-4.18) ******** 10****25**** (3****σ**** range)**

**  ****m****ββ****= 0.22 – 0.58 eV (3****σ**** range****) **

***Klapdor-Kleingrothaus et al.***
***Physics Letters B 586 (2004) 198-212, Nuc. Instrum. Meth.,A 522, 371(2004).***

**Best value: 1.19x10****25**** y**

***Nuclear matrix element of Rodin et al., Erratum ***
***nucl-th/0706.4304***

**CUORICINO and the KKDK claim of evidence**

- Evidence of          decay of 76Ge claimed by a subset of the Heidelberg-Moscow collaboration (Klapdor-Kleingrothaus et al.)

- (Klapdor et al.)

- T1/20v (130Te)

- Choose a nuclear model

**Compare experiments with different isotopes **

*  ** *

- T1/2(76Ge)=1.19 x 1025y equivelent to T1/2(130Te) = 3 x 1024y, CUORICINO bound

- Use three recent nuclear structure models:

## T1/2 x 1024 y for 130Te 

**T****1/2**** x 10****24**** y for ****130****Te**

**QRPA Jyv****ä****skyl****ä et al.**

**Shell model**

**QRPA Tuebingen**** et al.**

**CUORICINO and the ****76****Ge claim of evidence**

- The KKDK claim half life range (3) is converted into a corresponding range for 130Te using the three mentioned models

**Nuclear models**

##                                 ERRATUM

- Since this analysis we have learned that we missed a
- New analysis by Klapdor-Kleingrothaus and Krivosheina
- That included only pulse shape analysis data. The new
- Half life from Heidelberg-Moscow Experiment data is

- This will make it a bit more difficult to confirm or refute this result with CUORICINO with one QRPA, but a bit more readibly with Shell model matrix elements.

- Thank you Vladimir Tretyak for pointing that out!

## CUORE sensitivity

## CUORE and the inverted hierarchy region

**Quasi-degenarate**

*S. Pascoli, S.T. Petcov*

**Inverted hierarchy**

**Normal hierarchy**

- M

- Lightest neutrino mass

## Conclusions

-  Bolometers represent a well established technique, very competitive for
-     neutrinoless DBD search
-  CUORICINO and NEMO-3 are presently the most sensitive 0DBD            running experiments, with chance to confirm the HM claim of evidence if this is correct
-  CUORICINO demonstrates the feasibility of a large scale bolometric
-  detector (CUORE) with good energy resolution and background
-  CUORE is a next generation detector; it is funded and is scheduled to begin operation in January 2011
-  Recent results on background suppression confirm the capability to
- explore the inverted hierarchy mass region with CUORE