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The Electron Capture Decay of 163Ho to Measure the Electron Neutrino Mass with sub-eV sensitivity

The Electron Capture Decay of 163Ho to Measure the Electron Neutrino Mass with sub-eV sensitivity

Objective

"HOLMES is aimed at directly measuring the electron neutrino mass using the electron capture (EC) decay of 163Ho.
The measurement of the absolute neutrino mass represents a major breakthrough in particle physics and cosmology. Due to their abundance as big-bang relics, massive neutrinos strongly affect the large-scale structure and dynamics of the universe. In addition, the knowledge of the scale of neutrino masses, together with their hierarchy pattern, is invaluable to clarify the origin of fermion masses beyond the Higgs mechanism.
The innovative approach of HOLMES consists in the calorimetric measurement of the energy released in the decay of 163Ho. In this way, all the atomic de-excitation energy is measured, except that carried away by the neutrino. A finite neutrino mass m causes a deformation of the energy spectrum which is truncated at Q-m, where Q is the EC transition energy. The sensitivity depends on Q - the lower the Q, the higher the sensitivity - and 163Ho is an ideal isotope with a Q around 2.5keV. The direct measurement exploits only energy and momentum conservation, and it is therefore completely model-independent. At the same time, the calorimetric measurement eliminates systematic uncertainties arising from the use of external beta sources, as in neutrino mass measurements with beta spectrometers, and minimizes the effect of the atomic de-excitation process uncertainties.
HOLMES will deploy a large array of low temperature microcalorimeters with implanted 163Ho nuclei. The resulting mass sensitivity will be as low as 0.4eV. HOLMES will be an important step forward in the direct neutrino mass measurement with a calorimetric approach as an alternative to spectrometry. It will also establish the potential of this approach to extend the sensitivity down to 0.1eV.
The detection techniques developed for HOLMES will have an impact in many frontier fields as astrophysics, material analysis, nuclear safety, archeometry, quantum communication."
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Principal Investigator

Stefano Ragazzi (Prof.)

Host institution

ISTITUTO NAZIONALE DI FISICA NUCLEARE

Address

Via Enrico Fermi 40
00044 Frascati

Italy

Activity type

Research Organisations

EU Contribution

€ 1 638 466,50

Principal Investigator

Stefano Ragazzi (Prof.)

Administrative Contact

Marilena Perrone (Dr.)

Beneficiaries (2)

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ISTITUTO NAZIONALE DI FISICA NUCLEARE

Italy

EU Contribution

€ 1 638 466,50

UNIVERSITA' DEGLI STUDI DI MILANO-BICOCCA

Italy

EU Contribution

€ 1 418 600,50

Project information

Grant agreement ID: 340321

Status

Closed project

  • Start date

    1 February 2014

  • End date

    31 January 2019

Funded under:

FP7-IDEAS-ERC

  • Overall budget:

    € 3 057 067

  • EU contribution

    € 3 057 067

Hosted by:

ISTITUTO NAZIONALE DI FISICA NUCLEARE

Italy