ARIA’s modules are being leak-tested at CERN before travelling to Sardinia, Italy. The top, bottom and one standard column module have now been lined up horizontally to test their alignment. (Image: J. Ordan/CERN)
Producing the purest argon ever made is no mean feat, in fact it needs a column 26 metres taller than the Eiffel Tower.
CERN is part of a project, called ARIA, to construct a 350-metre-tall distillation tower that will be used to purify liquid argon for scientific and, in a second phase, medical use.
The full tower, composed of 28 identical modules plus a top (condenser) and a bottom (re-boiler) special module, will be installed in a disused mine site in Sardinia, Italy.
The project is was initiated to supply the purest argon possible to the international dark matter experiment DarkSide at INFN’s Gran Sasso National Laboratories. DarkSide is a dual-phase liquid-argon time-projection chamber that aims to detect the possible passage of a dark matter particle in the form of a Weakly Interacting Massive Particle (WIMP) when it hits the argon nuclei contained in the detector. Since this WIMP-nuclei interaction is predicted to be extremely rare, the detector must contain only the purest argon possible, so as not to accidentally produce a spurious signal.
ARIA has been designed to produce this extra-pure argon. Atmospheric argon contains many “impurities” such as water, oxygen, krypton and argon-39, an isotope of argon, which are all sources of unwanted signals. Argon from underground sources is already depleted from the argon-39 isotope by a factor of 1400, but this is still not enough for dark-matter research. ARIA is designed to purify underground argon by a further factor of 100.
For more information, read this article.
The LHCb detector in open configuration. (Image: Anna Pantelia/CERN)
For the first time, the LHCb experiment at CERN has collected data simultaneously in collider and in fixed-target modes. With this, the LHCb special run is even more special.
The past two weeks have been devoted to special runs of the Large Hadron Collider (LHC), at the end of the LHC 2017 proton run and before the winter shutdown. One run involved proton collisions at an energy of 5.02 TeV, mainly to set a reference to compare with lead-ion collision data. What was exceptional this year is that a tiny quantity of neon gas was injected into the beam pipe near the LHCb experiment’s interaction point. This allowed physicists to collect proton-neon at the same time as proton-proton collision data.
When (noble) gases are injected into the beam pipe to collide with protons, the LHCb experiment is in “fixed-target” mode, in contrast to the standard “collider” mode. But unlike traditional fixed target experiments, where the beam of accelerated particles is directed at a dense solid or liquid target, here LHC protons are colliding with a handful of neon nuclei injected near the collision point and floating in the beam pipe. These nuclei slightly pollute the almost perfect LHC vacuum, but the conditions they create – where pressure is in the order of 10-7 millibar – are still considered to be typical of ultra-high vacuum environments.
There are two main reasons to collect proton-gas collision data at the LHC. On one hand, these data help understand nuclear effects (i.e. depending on the type of nuclei involved in the collisions), affecting the production of specific types of particles (J/ψ and D0 mesons), whose suppressed production is considered to be the hallmark of the quark-gluon plasma. The quark-gluon plasma is the state in which the matter filling the universe a few millionths of a second after the Big Bang was , when protons and neutrons had not yet formed, composed of quarks not binding together and then free to move on their own.
On the other hand, proton-neon interactions are important to also study cosmic rays – highly energetic particles, mostly protons, coming from outside the Solar System – when they collide with nuclei in the Earth’s atmosphere. Neon is one of the components of the Earth’s atmosphere and it is very similar in terms of nuclear size to the much more abundant nitrogen and oxygen.
This gas-injection technique was originally designed to measure the brightness of the accelerator's beams, but its potential was quickly recognised by the LHCb physicists and it is now also being used for dedicated physics measurements. In 2015 and 2016, the LHCb experiment already performed special proton-helium, proton-neon and proton-argon runs. In October this year, for eight hours only, the LHC accelerated and collided xenon nuclei, allowing the four large LHC experiments to record xenon-xenon collisions for the first time.
This recent 11-day proton-neon run will allow physicists to collect a dataset that is 100 times larger than all proton-neon collision data collected until now at the LHC, and the first results of the analyses are foreseen for next year.
Find out more on the LHCb website.
SESAME XAFS/XRF beamline scientist, Messaoud Harfouche, points out SESAME’s first monochromatic light. (Image: SESAME)
At 10:50 yesterday morning scientists at the pioneering SESAME light source saw First Monochromatic Light through the XAFS/XRF (X-ray absorption fine structure/X-ray fluorescence) spectroscopy beamline, signalling the start of the laboratory’s experimental programme. This beamline, SESAME’s first to come on stream, delivers X-ray light that will be used to carry out research in areas ranging from solid state physics to environmental science and archaeology.
“After years of preparation, it’s great to see light on target,” said XAFS/XRF beamline scientist Messaoud Harfouche. “We have a fantastic experimental programme ahead of us, starting with an experiment to investigate heavy metals contaminating soils in the region.”
The initial research programme will be carried out at two beamlines, the XAFS/XRF beamline and the Infrared (IR) spectromicroscopy beamline that is scheduled to join the XAFS/XRF beamline this year. Both have specific characteristics that make them appropriate for various areas of research. A third beamline, devoted to materials science, will come on stream in 2018.
“Our first three beamlines already give SESAME a wide range of research options to fulfil the needs of our research community,” said SESAME Scientific Director Giorgio Paolucci, “the future for light source research in the Middle East and neighbouring countries is looking very bright!”
First Light is an important step in the commissioning process of a new synchrotron light source, but it is nevertheless just one step on the way to full operation. The SESAME synchrotron is currently operating with a beam current of just over 80 milliamps, while the design value is 400 milliamps. Over the coming weeks and months as experiments get underway, the current will be gradually increased.
“SESAME is a major scientific and technological addition to research and education in the Middle East and beyond,” said Director of SESAME, Khaled Toukan. “Jordan supported the project financially and politically since its inception in 2004 for the benefit of science and peace in the region. The young scientists, physicists, engineers and administrators who have built SESAME, come for the first time from this part of the world.”
Among the subjects likely to be studied in early experiments are environmental pollution with a view to improving public health, as well as studies aimed at identifying new drugs for cancer therapy, and cultural heritage studies ranging from bioarcheology – the study of our ancestors – to investigations of ancient manuscripts.
“On behalf of the SESAME Council, I’d like to congratulate the SESAME staff on this wonderful milestone,” said President of the Council, Rolf Heuer. “SESAME is a great addition to the region’s research infrastructure, allowing scientists from the region access to the kind of facility that they previously had to travel to Europe or the US to use.”
Graphenea has been awarded an ISO 9001:2015 certificate for the “Design and development, manufacture and commercialization of high quality graphene products”. The certificate was awarded by SGS, the world's leading inspection, verification, testing and certification company. The certificate is a statement that our business strives to continue to meet customer requirements and expectations.
ISO 9001 is an internationally recognized standard of excellence in quality management systems that is based on eight principles: customer focus, leadership, involvement of people, process approach, system approach, continual improvement, fact-based decision making, and mutually beneficial supplier relationships. The certificate is proof that Graphenea has been excelling at each of those points, but is also a statement of commitment to continue excelling in the coming years as the company maintains its pivotal role in graphene technology and applications. Congratulations team Graphenea!
These striking features on Mars were caused by the planet’s crust stretching apart in response to ancient volcanic activity.
A team of scientists from the University of Manchester and Graphenea have produced pressure sensors based on graphene/polymer heterostructures that compete with existing technology. Two types of sensors were made, the first sustaining large maximum load up to 250 kPa, the other yielding unprecedented pressure sensitivity of 123 aF Pa-1 mm2 over a pressure scale of 80 kPa.
The sensors fall into the capacitive type, a common design that measures the motion of a freestanding membrane that moves under pressure towards a fixed electrode. Such sensors find their applications in a vast industrial space that includes biomedical sensing (ex. blood pressure monitoring), altitude sensing, depth sensing, and gas or liquid system leak testing.
The sensors are made by coating graphene with a polymer layer, for optimal trade-off between device performance and membrane yield – free-standing graphene has a tendency to stick to the substrate during the fabrication process, which is avoided with polymer reinforcement. The present devices have 100% fabrication yield. Optical and mechanical inspection reveals that the quality of the graphene is excellent after the two-step transfer fabrication process.
Figure: Sketch, photograph, and AFM image of graphene/polymer pressure sensors. Reproduced from Nanoscale 2017, Advance Article , DOI: 10.1039/C7NR04621A with permission from The Royal Society of Chemistry.
The first sensor type was shown to sustain an up to 250 kPa pressure difference. The sensor reacted to pressure changes and had a relaxation time of several seconds, on par with commercial polymer-based sensors. The second type of sensor was made by straining the membrane during fabrication, which resulted in better sensitivity. Suspended over a gap just 50 nm deep, the high-performance device yielded a sensitivity of 4.2 aF Pa-1, which is in the same ballpark as state-of-the-art commercial silicon- and polymer-based pressure sensors. The full pressure scale was 100 kPa, significantly outperforming metal-polymer sensors. Owing to the 2D nature of graphene, the sensitivity per unit area of the new device was over 30 times higher than for silicon pressure sensors and 5 times higher than for polymer-based sensors. Furthermore, graphene/polymer sensors should not suffer from brittle fatigue that silicon-based sensors experience over time and in humid conditions.
The work, published in the journal Nanoscale, highlights the potential of such graphene/polymer heterostructures for use in highly sensitive pressure sensors with a large operating range and excellent reliability.
