NEWS-SNO is the newest project of spherical gas detectors. The first of its kind, it will open a new window in the Dark Matter particle parameter space exploration.
Located in Sudbury, Canada, SNOLAB is the second deepest underground laboratory in the world. SNOLAB operates out of the active Vale Creighton Mine.
The very thick rock coverage (2000 m) allows to filter out the cosmic rays and their secondary particles while the low cross section particles like neutrinos or Dark Matter particles are able to cross the rock and reach the underground detector.
The main aims of the experiment will be to search for:
- Light Dark Matter particles with spin independent couplings, in the 0.1 – 5 GeV range; see below anticipated performances vs the current present experimental limits (Feb 2015)
- Kaluza Klein axions through their 2 photon decay
- Light Dark Matter particles with spin dependent couplings, through the use of H nuclei from Hydrogen rich gas such as CH4.
In the above figure, new calculated limits obtained for around 100 kg-days exposure with Ne/He/CH4 are shown, taking into account anticipated background from materials, a detector threshold set to 1 electron (i.e. 20 to 40 ev ee), and quenching factors extrapolated down to 100-200 eVNR.
ee: eV in electron equivelant energy
NR: eV in nuclear recoil equivelant energy
- The detector itself is a 1.4 m diameter spherical ultra pure copper vessel with a sensor at the center of the sphere, held by a rod bringing the high voltage.
- The large lead shielding. The archaelogical lead protects the detector from the local radioactivity of the surrounding cavern rock. A glovebox system is in design to reduce the amount of radon-dense air from entering the system
- Pipes bringing the gas in and circulating it.
- Gas, vacuum and purification system on the deck above
- Electronics (close to the detector), high voltage units and acquisition system on the deck
The detector will be operated with gas such as Ne, He, and parts CH4 at pressures as high as 10 bars. The present drawing shows a possible implementation in the Cube Hall of SNOLAB.