Noble liquids to rescue dark matter search
dark matter Partly funded through the ASPERA 1st common call, the DARWIN project aims at building a big future detector for dark matter search, using the very promising noble liquids technologies.



The Darkside experiment at INFN Gran Sasso lab

An ASPERA visit at the INFN Gran Sasso underground laboratory in October 2012 – people look at the new DarkSide experiment being constructed.
A noble liquid Time Projection Chamber (TPC) can offer a large, self-shielding, homogeneous and position sensitive WIMP detector. The relative size of the charge and light signals, as well as their timing allows efficient discrimination against electron recoil events, and good spatial resolution allows the identification of the neutron background. In addition, operating a LAr and a LXe target under similar experimental conditions will allow to measure the dependence of the rate with the target mass and to distinguish between spin-independent and spin-dependent couplings.

Among the challenges of the DARWIN R&D programme are the development of new detectors reducing the background and lowering the costs for such a big experiment, cryostat design, the purification of the noble liquids, the use of ultra-low radioactivity materials and shields, the safety aspects… DARWIN benefited from the help of the very first ASPERA common call with an amount around 600k€ allowing for the opening of 5 postdoc positions to work on R&D (in France, Italy, the Netherlands and Switzerland). “This call stimulated the community to join forces. Writing such a proposal really brought people together. We learnt a lot by being together.” said Laura Baudis. There are strong links between the DARWIN project and noble liquid ongoing experiments such as XENON, DarkSide or ArDM. “The current and near-future experiments act as R&D activities for DARWIN and we have collaborators involved in XENON, ArDM and DarkSide. Gathering these people would perhaps have happened without the ASPERA call, but probably much later. I hope that there will be more coordination in the future. We need continuation in funding R&D.” she added.

The construction of DARWIN could start by 2017 at the earliest and operation would start in 2018. It will likely be installed at the Gran Sasso underground laboratory after XENON1T and DarkSide, possibly reusing the large water and/or scintillator shields. The expected overall construction costs of the DARWIN argon and xenon detectors is about 100 M€.  

But where did the name come from?  “When we started the project, I was precisely looking for a name. I was once in an airport and saw a plane from the DARWIN Swiss-based airline. And then I thought, well, this is a good name!” said Laura Baudis. Hopefully such a large project will fly!

    Submitted by Arnaud Marsollier (CERN)