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?
- Better Brains With Beer
- How A Former Naturopath Can Help Unravel The Trickery of Alternative Medicine
- Finding All-Hadronic Top - Again
- Brexit, the EU Now Has its Puerto Rico.
- Tidal Disruption Event: Black Hole Eats Star, Beams Signal To Earth
- 9,000 Years: Origin Of Farmed Rice Gets Pushed Back
- Psychiatric Diagnoses Not Valid For African-Americans, Says Sociologist
- " And all that science, I don't understand - it's just my job five days a week Pretty sure that..."
- "Good news for asteroid defense (it's not new news, but I only found out about it just now), this..."
- "Okay, first, this planet X, if it exists, always remains outside of Neptune if it exists - you..."
- "UPDATE - most recent paper has semimajor axes of ~380–980 AU, and masses of ~5–20..."
- "A better picture might be obtained by reading this article from an Irish journalist based in Russia..."
- What Happens To A Soccer Player’s Brain After Missing A Penalty Kick
- It’s Back to Shots for Flu Prevention
- ACSH Applauds Media Awareness of the Fentanyl Crisis
- Counting Bites Examined, to Help Decrease Food Intake
- The Safe And Unsafe Nutty Treats For Your Pup
- Mr. Potato Head Needs a New Warning Label!
- Should I stay or should I go?
- New cancer immunotherapy drugs linked to arthritis in some patients
- Simulations foresee hordes of colliding black holes in LIGO's future
- Analysis of genetic repeats suggests role for DNA instability in schizophrenia
- Analysis of media reporting reveals new information about snakebites and how and when they occur