Neutrinoless doublebeta decay and the SuperNEMO project' - PowerPoint PPT Presentation
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Neutrinoless doublebeta decay and the SuperNEMO project'
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Operates at the Fr jus Underground Laboratory in Savoie, France ... NEMO3 contains 10kg of isotopes primarily including enriched molybdenum (6.9kg) ... – PowerPoint PPT presentation
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Title: Neutrinoless doublebeta decay and the SuperNEMO project'
1
Neutrinoless double-beta decay and the SuperNEMO
project.
- Darren Price
- University of Manchester
- http//www.hep.man.ac.uk/u/darren
24 November, 2004
2
What is the NEMO project?
- NEMO Neutrino Ettore Majorana Observatory
- Main function is investigating neutrinoless
double-beta decay (0?bb) (also 2?bb) - Operates at the Fréjus Underground Laboratory in
Savoie, France - NEMO Collaboration working since 1989
- NEMO prototypes
- NEMO3 design began 1994
- about where we are now with SuperNEMO
- Planned to be running until 2007-8 when
hopefully(!) superseded by SuperNEMO
3
What is the NEMO project?
- Experimentally the double beta decays only
distinguished by their different electron energy
spectra
- Constructed to detect emitted electrons from
isotopes known to produce double beta decay,
whilst reducing any background effects.
4
What is the NEMO project?
- NEMO3 contains 10kg of isotopes primarily
including enriched molybdenum (6.9kg)
- Need to measure and tag all types of background
- same principles in SuperNEMO, need to eliminate
BG - ltmvgt sensitivity (0.15-0.5)
eV
- 0?bb observation gives information about absolute
mass scale
5
What is neutrinoless double-beta decay?
- Double beta decay - nucleus simultaneously
releases two electrons either with two or no
neutrinos in the final state - In 2?bb, two neutrinos observed, satisfies lepton
number conservation - In 0?bb, no neutrinos - implications for Standard
Model
6
What is neutrinoless double-beta decay?
- Despite lepton no. violation, 0?bb could exist
if - Neutrinos had non-zero mass (yes)
- Neutrinos are Majorana particles
- Prevailing belief - 0?bb exists, good
experimental indications, and preferred by
theorists! - Other processes can explain 0?bb, but only 0?bb
can test Majorana nature of neutrino with
absolute mass scale - 0?bb only practical approach to tell if Majorana
neutrino exists!
7
What is neutrinoless double-beta decay?
- Half life of 0?bb given by
- Gives ltmvgt - estimation of neutrino mass scale
- Electron energy plot for 2?bb and 0?bb
8
What is SuperNEMO?
- SuperNEMO is next generation 0?bb detector
- Much larger design - 100kg isotope (Se-82)
- planar geometry, 4 supermodules
- low BG, 5000 photomultipliers, passive shielding
- 10xNEMO3 (big detector - disadvantage)
- NEMO3 is testing feasibility for SuperNEMO
- need BG only from 2?
- need DE/E10 at 1MeV (better than NEMO3)
- demonstrated at UCL/Dubna
9
What is SuperNEMO?
- Boulby mine - attractive experimental site
- Timescale
- 2004-05 Scintillator RD
- 2005-06 Design proposal and prototype
- 2007-10 Production
- 2009-10 Start taking data
- 2014 Planned sensitivity
- ltmvgt sensitivity 0.04eV
10
What am I doing?
- New experiment - new problems
- Figuring out how GEANT models 0?bb/2?bb including
decay kinematics - Detector geometry materials (tracking,
scintillator) - Backscattering results
- Energy resolution
11
Considerations
- ?-ray effects
- BG and energy resolution
- Mechanics of detection
- lasers for daughter particle?
- wires to track electrons?
- Active/passive scintillator?
12
Some results so far...
- Backscattered electrons
- percentage backscattered
- energy distribution
13
Some results so far...
14
Some results so far...
15
Neutrinoless double-beta decay and the SuperNEMO
project.
- Darren Price
- University of Manchester
- http//www.hep.man.ac.uk/u/darren
24 November, 2004
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