Xenon1T is Xenon’s program latest step/stage of development in their detection of dark matter efforts. It is the third detector created after Xenon10 and Xenon100, and the first one that actually has the technical capacity of generating undeniable evidence of the existence of dark matter through experimentation and eventual detection. Before we head onto the details of that, let’s first say a few things about dark matter.
Dark matter is a type of a completely non-interacting and non-radiating matter that supposedly constitutes the largest portion of the total mass of our universe. Its existence is currently hypothetical as there has not been a way to detect it yet, and we have only come to the conclusion that it should exist by observing a wide variety of astronomical facts that can’t be explained otherwise. These observations include the formation of galaxy clusters, the existence of gravitational lensing, the pattern of galaxy rotational curves, the distortions in redshift-space, and many more. However, observing the results/effects of something that supposedly exists isn’t enough for scientists to prove its existence, so we need to run experiments that will help us detect dark matter directly. But how can you devise experiments that detect something that you don’t even know exactly what it is, and in addition to that, how can we possibly detect something that doesn’t interact with regular mass in any way?
The 135 scientists of the Xenon program have devised a way to deal with this complexity by using super-sensitive detection methods. They basically fill a big tank with ultra-pure xenon which is a noble gas and then monitor its scintillation and ionization levels for a long period of time with the hope to detect excess nuclear recoil events. Because dark matter is so non-interactive, the number of excessive events may be too little for a given amount of xenon volume, and the accuracy with which we need to predict the “expected” nuclear recoil events enters the territory of humongous practical difficulties that stem from a number of factors. For example, the intrinsic radioactivity of all materials that can be possibly used for the building of the detector is a huge problem that adds greatly to the complexity of predicting the expected number of “standard” nuclear recoil events.
After the Xenon10 that contained 15 kg of liquid xenon, the team built the Xenon100 which was sized up to hold 165 kg of the same material, and finally built Xenon1T last year which is able to hold 3.5 tons of ultra radio-pure liquid xenon at a temperature of -95C! This huge amount of xenon makes it easier to detect excess recoil events as those will be larger in number and thus won’t be inside the range of attributing them to other factors. Talking about other factors, for Xenon1T, the team has sourced the most non-radioactive materials that they could find for their latest detector, and have built it deep inside the Gran Sasso mountain, further shielding it from outside radio noise. The first experiment results show that Xenon1T is 100 times more sensitive than the previous Xenon100, allowing a confidence level of dark matter detection of up to 90%! This opens up a new era in the field, with hopefully lots of exciting announcements to come during the next couple of years.