The Super-CDMS dark-matter search has released two days ago the results from the analysis of nine months of data taking. The experiment has excellent sensitivity to weak interacting massive particles producing inelastic scattering with the Germanium in the detector.
The detector is composed of fifteen cylindrical 0.6 kg crystals stacked in groups of three, equipped with ionization and phonon detectors that are capable of measuring the energy of the signals. From that the recoil energy can be derived, and a rough estimate of WIMP candidates mass. The towers are kept at close to absolute zero temperature in the Soudan mine, where backgrounds from cosmic rays and other sources are very small.
The search revealed a total of 11 phonon candidates, when 6.1+1.1-0.8 were expected from the considered background sources. This is only a mild excess, that happens by chance more than once in twenty trials (p=0.065). However, one of the seven considered detectors saw 3 energetic events, while its background prediction was of only 0.13+0.06-0.04 events. According to the CDMS paper this corresponds to a 4x10^-4 probability (I calculate 0.00054). That's a 3.4 standard deviations effect, but do not get excited...
In fact, the paper is careful to point out that the excess (three high-energy events) concentrates in the only detector which "has a ionization guard electrode shorted to ground". They suggest that their background prediction was therefore possibly incorrect.
The graph above shows the detected energy of the 11 candidates, compared with a model of possible signals from WIMPS of masses between 5 and 15 GeV. The three events detected by the "shorted" detector are in yellow.
The interim conclusions of the search (which is ongoing) are that a number of tentative signals observed by other experiments are strongly disfavoured; these include CoGeNT and CDMS II.
For more information please see the preprint.
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- How Gut Bacteria Ensure A Healthy Brain – and Could Play A Role In Treating Depression
- Researchers Created A Laser Bullet To See What It Would Look Like - And Here It Is
- Erupting Bardarbunga Volcano In Iceland Sits On A Massive Magma Hot Spot
- The Strange Organic Molecules In Titan's Atmosphere
- We're Too Late To Prevent 137,000 More Ebola Cases, Says Epidemiology Paper
- ASTEROIDS Act: Who Owns Space?
- The Quote Of The Week - Shocked And Disappointed
- "/* Science advances as much by mistakes as by plans. */ Apparently the mainstream physicists are..."
- "Part of being a theorist in any subfield is trying to explain the results that we have in hand..."
- "This essay interested me immensely. My father claimed to be an 'atheist' all his life but..."
- "Not all of us are explorers, much less pioneers. The author is certainly not the latter and too..."
- " Obviously 300% more fish farming means more illnesses and more antibiotic use.Is it really..."
- How to sell a toxic pesticide the smart way–call it organic
- Leftist dystopia? Anti-technology fever animates opposition to GMOs and other ‘disruptive’ technologies
- CDC faced a nearly impossible balancing act with Ebola, and failed
- Why Chobani reversed course, making yoghurt only from milk from cows not fed GMO grain
- Monterey, California, hotbed of anti-GMO activism, home to new GMO corn farm
- Evolution is sometimes messy or even outright ridiculous