Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Xenon outs WIMPs

02.05.2002


The UK’s Dark Matter Collaboration’s detector lab in Buolby Mine, Yorkshire.


Underneath the mine the WIMP detector is shielded from cosmic rays.


Dark-matter detector could pin down the Universe’s missing mass.

Researchers in London are building a cheap dark-matter detector that should be able to spot the exotic particles called WIMPs that are suspected of hiding most of the Universe’s missing mass1.

A prototype of the detector has just shown, for the first time, that it can spot something as close to a WIMP as it’s possible to produce in the lab.



WIMP stands for ’weakly interacting massive particle’. If WIMPs exist at all, they are thought to be hefty compared to the protons and neutrons in an atomic nucleus, but to barely interact with these components of normal matter.

Physicists believe that WIMPs make up as much as 99% of the total mass of the Universe. Astronomers can’t see this matter - hence its ’dark’ moniker - but they can see its gravitational effects on the way the stars and gas in galaxies rotate.

Even if billions of WIMPs are streaming through our bodies, they don’t have any effect. So WIMP-hunting could be a frustrating affair - like trying to fish for shrimps using the net from a football goal.

Several experiments are currently going to great lengths in the search for WIMPS. The problem is that detectors capable of WIMP-spotting will probably pick up other cosmic particles, too, swamping the WIMP signal. Cosmic rays - high-energy particles of normal matter from space - and radioactive emissions would also register.

To shield a WIMP-detector from cosmic rays, it must be placed deep underground. The UK Dark Matter Collaboration (UKDMC) houses detectors at a depth of 1,100 metres in a salt mine in Yorkshire. Another array in Italy is buried in a tunnel beneath a mountain.

It would all be a lot easier if a detector could differentiate between a cosmic ray and a WIMP. Last year Alex Howard and co-workers at Imperial College, London, proposed a new type of WIMP detector that could, in principle, do just that. The simple device contains liquid and gaseous xenon.

Howard’s team said that WIMPs entering the detector would occasionally collide with the nucleus of a xenon atom, causing a brief flash of light called a primary scintillation and removing an electron from the atom. An electric field would pull these electrons through the liquid into the xenon gas, where they would induce a secondary scintillation flash.

These two distinct events are crucial to WIMP identification. Other particles, such as cosmic rays, induce the same processes. But the brightness of the primary and secondary scintillations would be different for WIMPs, cosmic rays and other particles.

The closest thing to a WIMP that the researchers could use readily to test their device is a neutron. So they teamed up with Farhat Beg and colleagues, also at Imperial, who have developed a cheap and convenient table-top source of neutron beams called a plasma focus. Neutrons for scientific research are usually generated in nuclear reactors.

Using this source, the Imperial researchers show that the xenon detector spots and identifies neutrons, implying that it should be able to do the same with WIMPs. Indeed, neutrons give a signal so much like that of WIMPs that the remaining challenge will be to tell them apart.

"We’re now making a full-scale detector," Howard says. They hope to install it in the UKDMC mine in the next 12 to 18 months.

References

  1. Beg, F. N. et al. Table-top neutron source for characterization and calibration of dark matter detectors. Applied Physics Letters, 80, 3009 - 3011, (2002).

PHILIP BALL | © Nature News Service

More articles from Physics and Astronomy:

nachricht Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University

nachricht Astrophysicists explain the mysterious behavior of cosmic rays
18.08.2017 | Moscow Institute of Physics and Technology

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>