XeSAT2017: Online krypton and radon removal for the XENON1T experiment

This talk by Michael Murra (slides) was presented at the XeSAT2017 conference in Khon Kaen, Thailand, from 3. – 7. April 2017.

The  main background for the XENON1T experiment are the intrinsic contaminants krypton and radon in the xenon gas. Instead of purifying the xenon once before starting the science run we were able to operate our distillation column in a closed loop with the XENON1T detector system running during its commissioning phase. This resulted into reducing the krypton concentration quickly below 1 ppt (parts per trillion, 1 ppt = 10^(-12) mol/mol) without emptying and refilling of the detector.

In addition, the column was operated in the same closed loop in inverse mode in order to reduce Rn-222 by about 20% during the first science run.

This so-called online removal for both noble gases along with the working principle of the distillation system are presented within this talk.

SAIP 2017: Latest results from XENON1T

At the 62nd annual conference of the South African Institute of Physics (SAIP), hosted by the University of Stellenbosch, Jacques Pienaar presented the results of our first science run with XENON1T. While a dark matter particle candidate still eludes us, we are able to demonstrate that for the first time a tonne-scale liquid Xenon dark matter detector is not only operating, but doing so very successfully.

The work done up to this point has given us a thorough understanding of the electronic and nuclear recoil response in our detector, which we can use to look for dark matter candidates. This of course is just the start. In this first result we had an exposure of only 0.1 ton.years, but our design goal is 2 ton.years. Therefore much work still lies ahead to probe for dark matter, and indeed we have more than 3 times as much data available already to push the bounds of our knowledge further. Stay tuned!

Modulation results from Xenon100 presented at PASCOS 2017 conference.

On Tuesday 20th of June, we presented our latest results on Electronic Recoil Modulations with 4 years of Xenon100 data at the PASCOS 2017 conference held in Madrid. After a short introduction, by M.L. Benabderrahmane, to the dark matter modulation as a signal, the main results have been presented, namely the test statistics of unbinned profile likelihood to search for the modulation period using three different sets of data. The first set contains the single scatter events in the energy range 2-5.8keV, the second set contains Multiple scatter events in the same energy range and the last one contains single scatters in the energy range 6-20keV. The last two samples are used as a sideband. The results of the likelihood gives a period of 431 days which is different from the one observed by the DAMA/LIBRA collaboration. Our single scatter modulation at 431 days has a global significance below 2sigma. The local test statistics for one year period gives a 1.8sigma. Similarity of the spectra between the two control samples and the signal sample disfavors the possibility for a modulation due to Dark Matter interaction.

Talk at WIN2017: First Results from the XENON1T experiment

This talk by Sara Diglio (slides) was presented at the WIN2017 conference at the University of California in  Irvine, from June 19 – 24, 2017.

ReStoX is an original cryogenic system designed for experiments that make use of high quantities of liquid xenon. It allows to store the total amount of xenon in gaseous, liquid or solid phase and to fill it into the detector vessel under high purity conditions. The system is crucial in case of emergencies that might require a fast recovering of the whole xenon present in the detector. ReStoX is currently being used by the XENON1T experiment and a future upgrade for XENONnT has already started.

On Tuesday, May 30, we presented the first XENON1T results in a seminar at LNGS, the laboratory where our experiment is hosted. The seminar was presented by Marco Selvi (INFN Bologna) in the Fermi room, the main auditorium at LNGS, and introduced by the LNGS director prof. Stefano Ragazzi in front of about 40 scientists.

After a short introduction on Dark Matter (you may guess that at LNGS they are well aware of the details of this physics puzzle! ), we described the construction and commissioning phase of the various systems crucial to run our detector.

We then focused mainly on the performances of XENON1T in the first science run,
where we reached the lowest ER background ever achieved in a dark matter experiment.

Also our sensitivity is very good, being it also the best out of the various direct search dark matter experiment, even with just 34 days of data acquisition.

With our result, XENON1T (and LNGS with) is back at the frontline of the race to finally detect dark matter particles … we look forward to analyse the already acquired >70 days of data !