Direct Dark Matter Detection [A review]

Typically when an experiment is deemed inadequate and no longer worth running, the data taking will be stopped, final results will be published, and then the detector will be disassembled and valuable components usually taken back to the institutes that bought them for use in the department, or for prototyping.

Once this is done and the lab space is clear, the space will be re-used with something else... Harder Faster Stronger Better

Either that or the current detector will be modified in some way to make it better or enhanced.

It is quite common for collaborations to do a proof of principle detector, a small version to show that they know what they are doing. And when funding comes, built the full version.

The search has been going on for a long time, I think the major players if i am not mistaken are Boulby, GranSasso, SNOLAB and South Dakota I want to say there is another location in Europe, either France or Spain but i am not sure.

The good thing about the search is that there is a wide range of techniques and what logically can be done is that if dark matter ever gets observed in say... a cryogenic crystal, we should be able to take that and figure out what we expect in other detectors. We are in a period where the first ton scale experiment will be coming online in a year, but there are plans for bigger ones too. So in the next couple of ears there should be two or three ton scale experiments with Liquid Argon and Liquid Xenon.

ErosA433
This is in general not all that 'clean' as you point out. This is because the SNO Acrylic vessel at the time the video was made, had been sat open to mine air for a few years. Thus sending people into it it wouldn't really matter so much what they are wearing because it is already fairly dirty.

Thanks, that explains why they weren't wearing more rigorous "clean room" gear.

Thanks for the facilities overview too, I didn't realize SNO was the deepest. It must get a little warm down there. Is that muon density on the vertical axis of that graphic?

ErosA433
Harder Faster Stronger Better

Thanks, I probably could have guessed that answer but that's just the simplified version for those of us who don't know enough of the technical stuff.

I thought you might say something like the old facilities were having a hard time discriminating from background sources not originating from dark matter or something like that, maybe due to impurities or other non-dark matter sources, so as a result the newer facilities/detectors were striving for higher purity levels, for example. But you refer to "ton scale experiments", is this a reference to a larger detection medium or "target" and therefore a greater chance of detection? If so then we might add "bigger" to "Harder Faster Stronger Better"?

More shallow facilities are feasible research centres, but the muon shielding has to be more robust. It also means that you have more dead-time.

Dead-time is basically samples of data which contains no information of any use, because either the electronics have to reset, or the detector has to reset (in the case of a bubble chamber for example you have to recompress the target liquid) and during these periods, you do not collect data.

So shallow sites just mean that 1) You have to be able to detect muons passing through your detector with extremely high efficiency and 2) your neutrino shielding has to be very thick, because muons also cause neutron spallation.

When I say ton scale it really is just raw physical active mass used for data taking, DEAP for example is actually a detector filled with 3.6 Tons of Liquid Argon (when it is complete) In order to reduce issues with backgrounds coming from surfaces a smaller volume within the 3.6 Tons is defined as the active volume, and events which reconstruct inside this volume only are considered a part of the search.

Typically, unless you can be absolutely background free, going bigger gives you more chance of an interaction. Its like catching butterflies, the bigger the net, the better the chance.