Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The search for dark matter widens

21.03.2018

New scintillation material shows promise in search for light dark matter particles

Astronomers have observed that galaxies rotate with such great speed they should be torn apart, yet they are not. It is as if some hidden mass is holding the galaxies together by exerting a gravitational force on ordinary matter.


Left: Excitation curve (blue diamonds) and emission curve (red circles) showing that almost all of the emission spectrum of the GaAs scintillator is outside the absorption band. Right: Simplified diagram of excitation and emission processes. The silicon donor provides a population of conduction band electrons that recombine with holes trapped on the boron acceptors. Electron excitations as little as 1.44 eV can produce 1.33 eV photons.

Credit: Stephen Derenzo, Lawrence Berkeley National Laboratory

This unknown mass is known as dark matter. Ordinary matter makes up only 5 percent of all content in the universe, whereas dark matter constitutes more than 25 percent of everything. The remaining 70 percent is known as dark energy, but no one has ever directly observed dark matter or dark energy.

In this week's issue of Journal of Applied Physics, by AIP Publishing, investigators report the discovery of a new material that may be able to directly detect dark matter. The material, known as a scintillator, should be sensitive to dark matter that is lighter than a proton. This will allow the search for dark matter to enter a largely unexplored mass range, below that of the proton.

Dark matter particles heavier than protons are known as weakly interacting massive particles, or WIMPs. Researchers have tried to detect these in several ways, including in underground laboratories where a large amount of shielding can be used, but, so far, they have all failed. To date, nothing is actually known about dark matter's mass, and its detection would have huge implications for our understanding of the universe.

The scintillator material reported in this work operates near absolute zero, or nearly minus 460 degrees Fahrenheit. It detects electrons recoiling from collisions with dark matter particles and consists of a target of ordinary matter, in this case gallium arsenide, or GaAs, doped by a small amount of other elements. The target emits a photon (a particle of light) after an electron in the target is excited to a high energy state through a collision with a dark matter particle.

The discovery represents the first time that n-type GaAs, chosen for its low band gap energy, has been used as a cryogenic scintillation detector. When the new scintillation detector is combined with a cryogenic photodetector -- which can detect light at very low temperatures -- the result will be, in the words of Stephen Derenzo, lead author on this week's report, "a workhorse useful in the search for dark matter in a largely unexplored mass range."

When the final device is constructed, experiments will be carried out deep underground to shield the detector from cosmic rays and other potential sources of false signals. One serious limitation of most scintillators is afterglow, also known as phosphorescence. Afterglow is a potential problem since it can mimic a dark matter detection and lead to a false signal. Data in this week's report show that no afterglow occurs with the new scintillator material -- a very promising result in the ongoing search for dark matter.

###

The article, "Cryogenic scintillation properties of n-type GaAs for the direct detection of MeV/c2 dark matter," is authored by S. Derenzo, E. Bourret, S. Hanrahan and G. Bizarri. The article will appear in the Journal of Applied Physics March 20, 2018 (DOI: 10.1063/1.5018343). After that date, it can be accessed at http://aip.scitation.org/doi/full/10.1063/1.5018343.

ABOUT THE JOURNAL

Journal of Applied Physics is an influential international journal publishing significant new experimental and theoretical results of applied physics research. See http://jap.aip.org.

Media Contact

Julia Majors
media@aip.org
301-209-3090

 @AIPPhysicsNews

http://www.aip.org 

Julia Majors | EurekAlert!

More articles from Materials Sciences:

nachricht From foam to bone: Plant cellulose can pave the way for healthy bone implants
19.03.2019 | University of British Columbia

nachricht Additive printing processes for flexible touchscreens: increased materials and cost efficiency
19.03.2019 | INM - Leibniz-Institut für Neue Materialien gGmbH

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Self-healing coating made of corn starch makes small scratches disappear through heat

Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.

Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

Im Focus: Heading towards a tsunami of light

Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.

"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...

Im Focus: Revealing the secret of the vacuum for the first time

New research group at the University of Jena combines theory and experiment to demonstrate for the first time certain physical processes in a quantum vacuum

For most people, a vacuum is an empty space. Quantum physics, on the other hand, assumes that even in this lowest-energy state, particles and antiparticles...

Im Focus: Sussex scientists one step closer to a clock that could replace GPS and Galileo

Physicists in the EPic Lab at University of Sussex make crucial development in global race to develop a portable atomic clock

Scientists in the Emergent Photonics Lab (EPic Lab) at the University of Sussex have made a breakthrough to a crucial element of an atomic clock - devices...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Molecular motors run in unison in a metal-organic framework

20.03.2019 | Life Sciences

Active substance from plant slows down aggressive eye cancer

20.03.2019 | Life Sciences

Novel sensor system improves reliability of high-temperature humidity measurements

20.03.2019 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>