A ground-breaking detector that aims to use quartz to capture high-frequency
gravitational waves has been built by researchers at the ARC Centre of
Excellence for Dark Matter Particle Physics (CDM) and The University of
Western Australia.
In its first 153 days of operation, two events were detected that could, in
principle, be high-frequency gravitational waves, which have not been
recorded by scientists before.
Such high-frequency gravitational waves may have been created by a
primordial black hole or a cloud of dark matter particles.
The results were published this month in the American Physical Society APS
Physics journal in an article titled “Rare Events Detected with a Bulk
Acoustic Wave High Frequency Gravitational Wave Antenna.”
Gravitational waves were originally predicted by Albert Einstein, who
theorized that the movement of astronomical objects could cause waves of
space-time curvature to be sent rippling through the universe, almost like
the waves caused by stones dropped into a flat pond. This prediction was
proven in 2015 by the first detection of a gravitational wave signal.
Scientists believe that low-frequency gravitational waves are caused by two
black holes spinning and merging into each other or a star disappearing into
a black hole.
Since then, a new era of gravitational wave research has begun but the
current generation of active detectors feature strong sensitivity to only
low-frequency signals; the detection of high-frequency gravitational waves
has remained an unexplored and extremely challenging front in astronomy.
Despite most attention devoted to low frequency gravitational waves, there
is a significant number of theoretical proposals for high-frequency GW
sources as well, for example, primordial black holes.
The new detector designed by the research team at the CDM to pick up
high-frequency gravitational waves is built around a quartz crystal bulk
acoustic wave resonator (BAW). At the heart of this device is a quartz
crystal disk that can vibrate at high frequencies due to acoustic waves
traveling through its thickness. These waves then induce electric charge
across the device, which can be detected by placing conducting plates on the
outer surfaces of the quartz disk.
The BAW device was connected to a superconducting quantum interference
device, known as SQUID, which acts as an extremely sensitive amplifier for
the low voltage signal from the quartz BAW. This assembly was placed in
multiple radiation shields to protect it from stray electromagnetic fields
and cooled to a low temperature to allow low energy acoustic vibrations of
the quartz crystal to be detected as large voltages with the help of the
SQUID amplifier.
The team, which included Dr. Maxim Goryachev, Professor Michael Tobar,
William Campbell, Ik Siong Heng, Serge Galliou and Professor Eugene Ivanov
will now work to determine the nature of the signal, potentially confirming
the detection of high-frequency gravitational waves.
Professor Tobar said a gravitational wave was just one possible candidate
that was detected, but other explanations for the result could be the
presence of charge particles or mechanical stress build up, a meteor event
or an internal atomic process. It might also be due to a very high mass dark
matter candidates interacting with the detector.
“It’s exciting that this event has shown that the new detector is sensitive
and giving us results, but now we have to determine exactly what those
results mean,” Professor Tobar said.
“With this work, we have demonstrated for the first time that these devices
can be used as highly sensitive gravitational wave detectors.
“This experiment is one of only two currently active in the world searching
for high-frequency gravitational waves at these frequencies and we have
plans to extend our reach to even higher frequencies, where no other
experiments have looked before.
“The development of this technology could potentially provide the first
detection of gravitational waves at these high frequencies, giving us new
insight into this area of gravitational wave astronomy.
“The next generation of the experiment will involve building a clone of the
detector and a muon detector sensitive to cosmic particles. If two detectors
find the presence of gravitational waves, that will be really exciting.”
Reference:
Rare Events Detected with a Bulk Acoustic Wave High Frequency Gravitational
Wave Antenna by Maxim Goryachev, William M. Campbell, Ik Siong Heng, Serge
Galliou, Eugene N. Ivanov and Michael E. Tobar, 12 August 2021, APS Physics.
DOI: 10.1103/PhysRevLett.127.071102
No comments:
Post a Comment