Event calendar D-PHYS

Date	24.05.2017
Time	11:15
Place	PSI Area West WHGA/001
Speaker	Angelo Nucciotti
Area of expertise	Physics
Host	Dep. Physik
Contact
Abstract	The detection of neutrino oscillations has proved that neu trinos are massive particles but the assessment of their absolute mass scale is still an oustanding challenge in tod ay particle physics and cosmology. Beta or electron capture spectrum end-point study is curr ently the only experimental method which can provide a model independent measurement of the absolute scale of ne utrino mass. Within this framework the European Research Council has funded HOLMES, a new experiment to dire ctly measure the neutrino mass. HOLMES will perform a calorimetric measurement of the energy releas ed in the electron capture decay of the artificial isotope 163Ho. This measurement was originally proposed in 1982 b y A. De Rujula and M. Lusignoli, but only in the last decade the technological progress in detectors developme nt allowed to design a sensitive experiment. In a calorimetric measurement the energy released in the de cay process is entirely contained into the detector, except for the fraction taken away by the neutrino. This app roach eliminates both the problematics connected to the use of an external source and the systematic uncertainti es arising from decays on excited final states. The most suitable detectors for this type of measurement are l ow temperature thermal detectors, where all the energy released into an absorber is converted into a temper ature increase that can be measured by a sensitive thermometer directly coupled with the absorber. HOLMES will deploy a large array of low temperature microca lorimeters with implanted 163Ho nuclei. The resulting neutrino mass statistical sensitivity will be as low as 0.4 eV, thereby making HOLMES an important step forward in the direct neutrino mass measurement with a calo rimetric approach as an alternative to spectrometry. HOLMES will also establish the potential of this approach to extend the sensitivity down to 0.1 eV and lower. In order to reach a sub-eV sensitivity in its optimal config uration HOLMES will collect about 3x10^13 decays with an instrumental energy resolution of about 1 eV FWHM and a ti me resolution of about 1 μs. For a total measuring time of 3 years, this requires a total 163Ho activity of about 300 kBq. Deploying an array of 1000 detectors, each pixel must contain an 163Ho activity of about 300 Bq. The gradual array deployment is expected to start in late 2017. In this seminar I will first give a broad and general overvi ew on the neutrino mass and the experimental approaches for its direct measurement. Then I will outlin e the HOLMES project with its technical challenges, and its status and perspectives. In particular I will present t he status of the HOLMES activities concerning the 163Ho isotope production and purification, the detector array d evelopment and testing, the detector read-out installation, and the setting up of the system for isotope em bedding.

Date

24.05.2017

Time

11:15

Place

PSI Area West
WHGA/001

Speaker

Angelo Nucciotti

Area of expertise

Physics

Host

Dep. Physik

Contact

Abstract

The detection of neutrino oscillations has proved that neu trinos are massive particles but the assessment of their absolute mass scale is still an oustanding challenge in tod ay particle physics and cosmology. Beta or electron capture spectrum end-point study is curr ently the only experimental method which can provide a model independent measurement of the absolute scale of ne utrino mass. Within this framework the European Research Council has funded HOLMES, a new experiment to dire ctly measure the neutrino mass. HOLMES will perform a calorimetric measurement of the energy releas ed in the electron capture decay of the artificial isotope 163Ho. This measurement was originally proposed in 1982 b y A. De Rujula and M. Lusignoli, but only in the last decade the technological progress in detectors developme nt allowed to design a sensitive experiment. In a calorimetric measurement the energy released in the de cay process is entirely contained into the detector, except for the fraction taken away by the neutrino. This app roach eliminates both the problematics connected to the use of an external source and the systematic uncertainti es arising from decays on excited final states. The most suitable detectors for this type of measurement are l ow temperature thermal detectors, where all the energy released into an absorber is converted into a temper ature increase that can be measured by a sensitive thermometer directly coupled with the absorber. HOLMES will deploy a large array of low temperature microca lorimeters with implanted 163Ho nuclei. The resulting neutrino mass statistical sensitivity will be as low as 0.4 eV, thereby making HOLMES an important step forward in the direct neutrino mass measurement with a calo rimetric approach as an alternative to spectrometry. HOLMES will also establish the potential of this approach to extend the sensitivity down to 0.1 eV and lower. In order to reach a sub-eV sensitivity in its optimal config uration HOLMES will collect about 3x10^13 decays with an instrumental energy resolution of about 1 eV FWHM and a ti me resolution of about 1 μs. For a total measuring time of 3 years, this requires a total 163Ho activity of about 300 kBq. Deploying an array of 1000 detectors, each pixel must contain an 163Ho activity of about 300 Bq. The gradual array deployment is expected to start in late 2017. In this seminar I will first give a broad and general overvi ew on the neutrino mass and the experimental approaches for its direct measurement. Then I will outlin e the HOLMES project with its technical challenges, and its status and perspectives. In particular I will present t he status of the HOLMES activities concerning the 163Ho isotope production and purification, the detector array d evelopment and testing, the detector read-out installation, and the setting up of the system for isotope em bedding.

HOLMES: measuring the electron neutrino mass with the electron capture decay of 16A<sub>3</sub>Ho