a dark rumour

there is an amusing rumour on the resonaances blog about cold dark matter

The CDMS experiment is a Cold Dark Matter Search experiment, looking for nuclear recoil in lab detectors, due to scattering of weakly interacting massive particles with normal matter.
[hmm, link is to UC site for CDMS – the Stanford CDMS website is password protected, don’t know if that is usual – I have some recollection of linking to CDMS at Stanford in the
past with no problems.]

CDMSI ran for several years, and reported upper bounds on WIMP masses and cross-sections, and CDMSII has been running for a while now with better everything.
The upper limits they find are interesting.

Now Resonaances blog reports a hot rumour that CDMS may have found something.

The essence of the rumour is based on three things:

three simultaneous seminars on CDMS results at some high profile places

rumour of an embargoed Nature paper in press

and, CDMS collaborators clamming up

If they have a detection it is extremely interesting.
Nobel Prize sort of interesting.

The comment section is worth reading, although it degenerates into political poo-flinging towards the end, but the most interesting thing about the current entry is the firm and slightly rude denial of any embargoed CDMS paper in Nature.
Something which people who publish in Nature would instantly have realised…
the dates were wrong, as were the inferences about Nature embargo rules and preprint circulation (now collaboration group rules on preprint might lead to such preprint embargos, but that is not Nature’s fault).

Science does have an issue come out on friday the 18th of Dec, but the press release would probably be on thursday rather than friday.
I’ve not seen any – NSF and DoE ought to be going nuts if there is a detection.

PS: this is the abstract of Cushman’s talk at CERN on friday 18th – 11am, Main Auditorium:

I will present new results from the recent blind analysis of 612-kg days (before cuts) of data using the CDMS germanium detectors at Soudan. CDMS uses ionization and athermal phonon signals to discriminate between candidate (nuclear recoil) and background (electron recoil) events in Ge crystals cooled to ~ 50 mK. Timing, yield and position information allows us to tune our expected background leakage into the signal region to 0.5 events. I will report on what we saw when we “opened the box”, whether we have seen WIMPs or not, and implications for future dark matter direct experiments.


Interesting possibility: I’ll be a skeptic and take the “under” – any announcement they’re making is a new, mo’better upper limit with maybe a 2.8 σ or so hint of a detection somewhere interesting

h/t Sean’s Facebook feed…

Doug at nanoscale views has an interesting perspective on the experiment


  1. #1 Ethan Siegel
    December 9, 2009

    I bet you that — whether they report that they’ve found anything or not — five years from now we will have set limits that push dark matter’s cross section with normal matter below anything CDMS would have detected by now.

  2. #2 Steinn Sigurdsson
    December 9, 2009

    I agree, there will be very strong bounds on dark matter within a few years, and quite possibly detections.
    The limits are very model dependent though, they assume essentially a standard model extended WIMP with some weak or superweak coupling to baryonic matter.

  3. #3 Therese
    December 11, 2009

    I tried to get some information out of a grad student here who works in the CDMS group, who told me they might give me a hint if I asked the right questions, but the effort was not particularly fruitful. If I had only convinced them to have a few more drinks, maybe I would’ve gotten something… I suppose a week isn’t too long to wait.

  4. #4 Ethan Siegel
    December 14, 2009

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