Dark matter: CRESST searches for ‘lightweights’

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The Earth, planets, stars, and galaxies form usually a manifest apportionment of a matter in a universe. Greater by distant is a share accounted for by invisible “dark matter”. Scientists have searched for a particles of dim matter in countless experiments – so far, in vain.

Mounting a CRESST initial setup (Photo: MPP)

Mounting a CRESST initial setup (Photo: MPP)

With a CRESST experiment, now a hunt radius can be intensely expanded: The CRESST detectors are being overhauled and are afterwards means to detect particles whose mass lies subsequent a stream dimensions range. As a consequence, a possibility of tracking dim matter down goes up.

Theoretical models and astrophysical observations leave frequency any doubt that dim matter exists: Its share is 5 times some-more than all manifest material. “So distant a approaching claimant for a dim matter molecule was suspicion to be a complicated particle, a supposed WIMP,” explains Dr. Federica Petricca, a researcher during a Max Planck Institute for Physics and orator of a CRESST examination (Cryogenic Rare Event Search with Superconducting Thermometers). “Most stream experiments therefore examine a dimensions operation between 10 and 1000 GeV/c^2.”

The stream reduce extent of 10 GeV/c^2 (GeV: gigaelectronvolt; c: speed of light) roughly corresponds to a mass of a CO atom. However, recently several new fanciful models have been grown with a intensity of elucidate long-standing problems, like a disproportion between a unnatural and a celebrated dim matter form in galaxies. Several of theses models spirit towards dim matter possibilities subsequent a mass of a normal WIMP.

Measurement record for light particles of dim matter

Now CRESST has achieved an critical step toward tracking down these intensity “lightweights”: In a long-term examination with one detector, a researchers achieved an appetite threshold of 307 eV. “With that, this detector is best matched for measurements between 0.5 and 4 GeV/c^2, improving a attraction by 100 times,” says Dr. Jean-Come Lanfranchi, scientist during a Chair for Experimental and Astroparticle Physics during Technical University of Munich.

“We now can detect particles that are intensely lighter than WIMPs – for instance dim matter particles with a weight allied to a proton, that has a mass of 0.94 GeV/c^2”, adds Petricca.

On a basement of a newly gained insights, a scientists will now supply a examination with a novel detectors. The subsequent dimensions cycle of CRESST is approaching to start during a finish of 2015 and final for one to dual years.

Experimental setup

The executive partial of all CRESST detectors is a clear of calcium tungstate. When a molecule hits one of a 3 clear atoms (calcium, tungsten, and oxygen), a detectors concurrently magnitude appetite and light signals from a collision that broach information about a inlet of a impinging particle.

In sequence to locate even a smallest probable heat and light signals, a detector modules are cooled to nearby comprehensive 0 (-273.15 degrees C). To discharge unfortunate credentials events, a CRESST scientists occupy – for one thing – materials with small healthy radioactivity. In addition, a examination stands in a world’s largest subterraneous laboratory, in a Italian towering Gran Sasso, and so is mostly safeguarded from vast rays.

What’s new?

  • CRESST will work in a destiny with smaller and – compared to commercially made materials – ultrapure crystals. With a reduced distance a reduce appetite threshold can be achieved. These crystals are grown during a Technical University of Munich and vaunt intensely low inherited radioactivity, creation a examination some-more sensitive.
  • The strange bronze clear land have been transposed with calcium tungstate. With this, a series of undesired effects due to healthy radioactivity on a steel surfaces can be strongly reduced.
  • The pointing of a light detector has been optimized – collisions of already famous particles can be some-more clearly renowned from collisions of dim matter particles.

Source: TUM