The Bajkal Neutrino Detector
In the last presentation of the 2017 conference, Grigory Domogatsky (right) described the Bajkal detector. It is 4km from the shore, constructed in 1998, the first one in a natural medium. It was built to investigate atmospheric neutrinos, search for diffuse flux of high-energy neutrinos, and for wimp annihilation in the Earth.
In 2003-2005 they upgraded it ot extend more strings at larger distance, to include a larger volume, and have a higher efficiency of detection.
Now they are doing another upgrade, for a gigaton volume detector, with an array spanning 1km in width and 6oo m in depth. Strings have 3 sections with 12 optical modules each.
The PMT used is from Hamamatsu, R7081-100, with a good (35%) quantum efficiency. The diameter is of 10 inches. The optical module includes the PMT and is embedded in a mu-metal cage, includes the electronics and is embedded in a pressure-resistance glass sphere. The main problem is the time synchronization. This is performed by LED beacon, with 6 blue LEDs pointing upward plus 6 pointing horizontally.
The speaker finally showed the “Dubna” cluster with an estimated energy of 1.9 PeV.
To conclude his presentation Domagatsky showed the cumulative number of clusters expected per year by the upgraded detector.