New instruments for Dark Matter

Things have been happening lately with experiments which could eventually shed some light on dark matter.

The IceCube Neutrino Observatory, which was completed last December, defiantly started data taking in its final configuration on Friday the 13:th of this month. Data from 5397 optical modules are recorded at a rate of 2370 events per second, and about 50 million events per day are sent North for analysis via satellite (unfortunately,
almost all are due to atmospheric muons, not neutrinos). We are expecting to take data with the completed IceCube for fifteen years at least, and analyses have to be designed to include ever more data without introducing biases. Neutrinos from dark matter annihilation are being searched for from different sources, including the Sun which is the prime target of the Stockholm group.

With the detector completed, there are several follow-up projects under discussion. One such project which was recently endorsed by the IceCube collaboration board, and where Stockholm is involved, is an improvement of the DeepCore subdetector for low energies (guess what the acronym PINGU stands for!). Among the physics aims is an improved sensitivity to dark matter on the scale of tens of GeV.
Another project open to OKC participation is DM-ice, a NaI direct detection experiment in the South Pole ice which would refute or confirm the DAMA claim of a yearly modulation signal, and maybe find a signal of its own.
DM-ice prototypes were attached to two of the last IceCube strings.

A long-standing puzzle which might be related to dark matter annihilation is the rising ratio of positrons to electrons in cosmic rays as a function of energy, reported by the PAMELA satellite detector. In a recent working group meeting we heard from Laura Rosetto(OKC/KTH) about the efforts to further cross-check this result and extend the energy range of the PAMELA result from 100 GeV to 300 GeV. PAMELA is not a new detector and nor is Fermi, another project with substantial OKC involvement. But using the magnetic field of the Earth as a spectrometer, Fermi can be used for measuring this ratio, as Joakim has already discussed on this blog.

Finally, the OKC projects do have competition: The long awaited spectrometer AMS-02 was installed on the International Space Station on Thursday, and according to Sam Ting datataking works flawlessly.
The geometrical acceptance of AMS-02 is about 20 times that of PAMELA, so it could provide a competitive measurement of the e+/e- ratio rather soon. A drop somewhere above 100GeV would support a dark matter interpretation since it could correspond to the mass of the annihilating dark matter particles.
We’ll see!

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