Home » News & Blogs » Helium, not dark matter, might explain DAMA’s strong signal
Bookmark and Share
Physics World Blog

Helium, not dark matter, might explain DAMA’s strong signal

16 Jan 2019, 07:23 UTC
Helium, not dark matter, might explain DAMA’s strong signal
(200 words excerpt, click title or image to see full post)

A long-standing and controversial claim by physicists in Italy to have detected dark matter might be the result of the unanticipated contamination of their photomultiplier tubes (PMTs). So argue researchers in the US, who reckon that a pattern of signal pulses recorded by the DAMA detector at Italy’s Gran Sasso National Laboratory could simply have been generated by small amounts of helium leaking into the experiment – a hypothesis that they say could be easily put to the test.

DAMA, run by Rita Bernabei of the University of Rome “Tor Vergata” and colleagues in Italy and China, consists of 25 cylindrical sodium iodide scintillators, each weighing 10 kg and capped at either end by a PMT. The idea is that a tiny fraction of any dark matter particles streaming through the detector will collide with nuclei, creating tiny flashes of light. When this light reaches the photocathode in each PMT, electrons are emitted via the photoelectric effect. These electrons are then “multiplied” in a high-voltage cascade through a series of dynodes, which produce a measurable electrical signal.
Bernabei and colleagues look for a roughly 1% sinusoidal variation in the rate of dark-matter collisions throughout the year – with a peak ...

Latest Vodcast

Latest Podcast

Advertise PTTU

NASA Picture of the Day

Astronomy Picture of the Day

astronomy_pod