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Millions of cosmic rays bombard the Earth’s atmosphere every second. These are naturally-occurring particles from outer space, which are extremely difficult to detect and measure. When they collide with nuclei in the upper atmosphere, these so-called primary cosmic rays produce showers of secondary cosmic rays that go on to reach the ground. The Large Hadron Collider forward (LHCf) experiment, one of the smallest of the LHC experiments, was set up to thoroughly investigate these elusive particles when LHC operation first began. This week, it resumed its studies of the properties of cosmic rays, in a five-day data-taking run, following the completion of upgrades to the detector during the second long shutdown of the machine.
“When page one of the LHC showed that the LHC was being filled for the LHCf data taking, we were very excited,” says Oscar Adriani, deputy spokesperson for LHCf.
This is LHCf’s first data-taking run at the LHC’s record collision energy of 13.6 TeV. The run also coincided with the record time that the LHC has been able to keep a fill without restarting, namely a total period of 57 hours. Running for longer means more efficient periods of data-taking for the experiments.
Primary cosmic rays can have very high energies – above 1017 eV – similar to those of the high-energy collisions that are produced in the LHC. Located 140 m from the ATLAS collision point of the LHC and measuring only 20cm by 40cm by 10cm, LHCf analyses neutral particles that have been thrown forward by collisions, mimicking the production of secondary cosmic rays in the Earth’s atmosphere. The experiment is able to analyse neutral particles because they are not deflected by the LHC’s strong magnetic field, and can measure their properties with extremely high precision.
This five-day run is likely to be the final LHCf run involving proton-proton collisions, because in the next data-taking period of Run 3 the collaboration hopes to study proton-oxygen collisions that better emulate the interaction of primary cosmic rays with the Earth’s atmosphere.
With the higher energy and higher statistics that Run 3 provides, LHCf is particularly looking out for particles called neutral kaons and neutral eta mesons. These are made up of a quark and an antiquark pair, including a strange quark. “The models that predict interaction with the atmosphere predict a certain number of secondary muons, but there is a mismatch between the expected and the detected numbers of muons,” explains Adriani. “By measuring the strange component produced at the LHC, we may be able to solve this muon puzzle.”
The LHC, with its high energy and controlled environment, provides the perfect place to simulate and study the hadronic interactions of cosmic rays. “High energy cosmic rays are still a mystery. They are very difficult to measure. You need huge detectors, and you cannot perform direct measurements while they are in orbit because the flux is too small,” continues Adriani. “So, LHCf is really the only experiment in the world that can shed some light on these interactions at very, very high energy. This is a critical element for cosmic ray physicists.”
ndinmore Wed, 09/28/2022 - 12:24 Byline Naomi Dinmore Publication Date Wed, 09/28/2022 - 09:52From 1 September 2022 until 31 August 2024, the important role of representing the CMS collaboration will be served by Patricia McBride (spokesperson), Wolfgang Adam (deputy spokesperson) and Lucia Silvestris (deputy spokesperson) – the ninth Spokesperson team of the CMS experiment.
The management team will take charge as the newly upgraded CMS detector collects and selects new physics data extracted from collision events at the LHC at the unprecedented energy of 13.6 TeV.
Read more on the CMS website.
thortala Tue, 08/30/2022 - 10:41 Publication Date Tue, 08/30/2022 - 10:35The ATLAS collaboration held its sixth Outstanding Achievement Awards ceremony at CERN on 23 June 2022. Once every two years, these awards recognise the invaluable technical work made across the collaboration in all areas.
After an extensive review of 84 nominated candidates, the ATLAS Collaboration Board Chair Advisory Group, acting as the Awards Committee, decided to assign awards to four individuals and five groups across diverse categories. The winners specialised in the fields of detector operation, upgrade, software, outreach, computing and combined performance during the period from August 2020 to January 2022.
“It was very difficult to select among the many excellent nominations,” highlight Hans-Christian Schultz-Coulon and Oleg Solovyanov, Awards Committee co-Chairs. “In particular, concerning the Muon New Small Wheel (NSW) award, hundreds of dedicated people did a tremendous job getting the project ready in time. These awards are intended to acknowledge a small fraction of the many efforts made throughout the collaboration.”
The excitement surrounding this year’s awards was particularly strong, as it was the first time in over two years that the winners could be applauded in person. Watching the teams walk up to the podium to receive their plaque and certificate, the future of the ATLAS collaboration seems bright!
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For outstanding contributions to the integration of large-radius tracking into the standard ATLAS reconstruction: Bingxuan Liu (Simon Fraser University), Matthias Danninger (Simon Fraser University), John Stupak (University of Oklahoma), Robin Newhouse (University of British Columbia), Giuliano Gustavino (University of Oklahoma, CERN) and Jackson Carl Burzynski (University of Massachusetts Amherst, Simon Fraser University):
(Image: CERN)For outstanding contributions to the completion of the NSW integration and surface commissioning within the LS2 schedule: Artur Coimbra (CERN), Aimilianos Koulouris (National Technological University of Athens, University of Aegean, CERN), Luigi Longo (CERN, Università del Salento), Alexander Naip Tuna (CERN), Rimsky Alejandro Rojas Caballero (Federico Santa María Technical University, University of Victoria), Olga Zormpa (National Centre for Scientific Research “Demokritos”), Chiara Arcangeletti (University of Victoria), Rongkun Wang (Harvard University, University of Chicago and University of Science and Technology of China), Liang Guan (University of Michigan), Siyuan Sun (University of Michigan) (not pictured), Emanuele Romano (INFN Sezione di Pavia), Estel Perez Codina (TRIUMF), Alam Toro (TRIUMF), Gerardo Vasquez (University of Victoria), Camila Pazos (Brandeis University), Giada Mancini (National Laboratory of Frascati) and Polyneikis Tzanis (National Technical University of Athens):
(Image: CERN)For outstanding contributions to the ATLAS outreach activities: Muhammad Alhroob (University of Oklahoma), Katarina Anthony (University of Udine), Steven Goldfarb (University of Melbourne), Clara Nellist (Radboud University) (not pictured), Elise Maria Le Boulicaut (Duke University) and Sascha Mehlhase (Ludwig-Maximilians-Universität München) (not pictured):
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This list is not exhaustive. See all the awards on the ATLAS website.
anschaef Wed, 07/20/2022 - 10:38 Byline ATLAS collaboration Publication Date Wed, 07/20/2022 - 10:22CMS PhD Thesis Award winners 2021
(Image: CMS)Each year, the CMS collaboration recognises exceptional PhD student work with the Thesis Award. To select the best theses of 2021, a Thesis Award committee of 29 CMS scientists was appointed by the Collaboration Board (CB) Chair.
From the 25 nominations received this year, three winners were selected by the committee and then endorsed by the CB: Michael Andrews (Carnegie Mellon University), Matteo Bonanomi (LLR – Institut Polytechnique de Paris) and Viktoria Hinger (Institute of High Energy Physics of the Austrian Academy of Sciences and Vienna University of Technology).
The evaluation was based on the originality of the thesis author’s personal contributions, clarity, quality of content, and impact within CMS and in the broader context of high-energy physics.
Read more on the CMS collaboration’s website.
CMS Young Researchers Prize 2022
(Image: CMS)The CMS collaboration also recognises the efforts and outstanding achievements of its younger members, honouring them with the CMS Young Researchers Prize. This endorsement of their skills and dedication not only paves the way for their future careers but also motivates other young researchers to excel in the field.
Each year since 2012, at least three members have been awarded the prize, which comprises cash and a memento, for their sustained contributions and dedication in any area of the collaboration’s activities.
Congratulations to this year’s prize recipients: Davide Ceresa (CERN), Rajdeep Mohan Chatterjee (University of Minnesota), Jan Kieseler (CERN) and Yuta Takahashi (University of Zurich).
Read more on the CMS collaboration’s website.
CMS Award 2021
(Image: CMS)The CMS collaboration is proud to have been successfully advancing knowledge, scientific research and technology for years, and all this would certainly not have been possible without the contribution of each of its members.
The CMS Award, which honours dedicated members of the CMS collaboration for their significant contributions and outstanding work, has been awarded every year since 2000. Nominations can be made by any CMS member, for work in a variety of fields, ranging from detector systems and coordination to outreach. The awardees are selected by a dedicated committee of five members, and the selection is then endorsed by the CMS Collaboration Board (CB) Chair.
To find out more about each of the forty-seven awardees who made incredible contributions in 2021, visit the CMS collaboration’s website!
anschaef Tue, 07/19/2022 - 10:04 Byline CMS collaboration Publication Date Tue, 07/19/2022 - 09:59On 14 June, LHCb, which comprises over 1000 authors and 400 PhD students, announced the winners of the 2022 PhD Thesis and Early-Career Scientist Awards. The LHCb Thesis Awards recognise excellent PhD theses and additional work that have made an exceptional contribution to LHCb. In parallel, the Early-Career Scientist prizes are awarded to recognise outstanding achievements of early-career scientists for the benefit of LHCb.
This year’s winners of the Thesis prize are Giulia Tulci (University of Pisa), Guillaume Pietrzyk (EPFL) and Mengzhen Wang (Tsinghua).
Maarten van Veghel (Groningen), Saverio Mariani (Florence), Sevda Esen (Zurich), Valeriia Zhovkovska (Orsay), Maarten Van Dijk (Lausanne), Fabio Ferrari (Bologna) and Vladyslav Orlov (CERN) were awarded the Early-Career prize.
“The Thesis prize is awarded to students who have performed exceptional research in their PhD and contributed fully to the collaboration,” explains Ulrik Egede, chair of the Thesis committee. “This year’s winners worked in charm CP violation and mixing and complex amplitude analyses for spectroscopy but also contributed to the trigger, novel FPGA-based tracking, outreach and the construction of the Upgrade I tracker.”
The prizes for outstanding contributions by early-career scientists were awarded for a wide range of activities. “The prizes this year recognised improvements to electron identification and reconstruction, real-time reconstruction of beam–gas collisions, the persistence of the data produced by the trigger and the development of LHCb's new luminometer system,” says Irina Nasteva, chair of the Early-Career Prize committee.
Irina and Ulrik agreed that the standard of the work carried out by the many individuals nominated for the prizes was very high and demonstrated the strength and breadth of the work performed by the younger colleagues at the experiment.
anschaef Tue, 07/19/2022 - 09:55 Byline LHCb collaboration Publication Date Tue, 07/19/2022 - 09:50From the tunnel that hosted the now-retired CERN Neutrinos to Gran Sasso (CNGS) facility, AWAKE (Advanced Wakefield Experiment) is looking to revolutionise the field of particle acceleration. The 23-institute-strong collaboration aims to introduce a viable and more efficient alternative to traditional radiofrequency acceleration – with charged particles (in this case, electrons) “surfing” on the waves of a plasma field (or “wakefield”) generated by a short, intense proton bunch fired through the plasma.
While plasma wakefields have been shown to produce acceleration gradients up to 1000 times superior to those achieved with radiofrequency cavities, their use in high-energy and particle physics experiments has been limited by the impractical nature of current techniques, which require the juxtaposition of several plasma sources to achieve high energies. AWAKE, on the other hand, is the first experiment to investigate the use of protons, rather than lasers or electron beams, to drive the plasma. To create the appropriate wakefields in the plasma for efficient electron acceleration, the long proton beam extracted towards AWAKE from the CERN Super Proton Synchrotron (SPS) needs to be broken up into smaller bunches in a process known as modulation. In a Physics Review Letters paper published on 6 July, the collaboration showed how such a modulation of the proton beam can be controlled by seeding the process with relativistic electrons – a crucial step towards a workable wakefield-based accelerator.
To grasp the concept of seeding, it is necessary to delve into the technology behind AWAKE. The proton beam from the SPS is injected into a vapour source containing rubidium, which is transformed into a plasma (a state of ionised gas) by a laser pulse that precedes the proton bunch. A short electron bunch can then be injected into the proton wake to be accelerated to high energy. For the electrons to ride the waves of the plasma efficiently, the wavelength of the proton bunch needs to equal the length of the short electron bunch. Luckily, the long proton beam from the SPS automatically breaks up into such small bunches when propagating through the plasma (it “self-modulates”), which is what allowed AWAKE to demonstrate the first acceleration of electrons using this technique in 2018.
“To preserve the reproducibility of the entire modulated proton beam, and thereby its ability to accelerate electrons, we devised a technique to control exactly when the modulation begins: we seed it with an initial electron bunch, different from the one that is targeted for acceleration. By injecting this bunch several hundreds of picoseconds before the protons enter the plasma, the front of the proton beam modulates in sync, creating a regular wakefield whose phase can be precisely measured”, explains Livio Verra, a physicist in the Lepton Accelerators and Facilities (ABP-LAF) section in the Beams department and the first author of the paper. Injection of the electron bunch whose acceleration the experiment is targeting can then be timed perfectly. The acceleration therefore becomes sustainable and controlled, producing an unparalleled overall gradient.
The figure shows the sum of ten consecutive time-resolved images of the self-modulated proton bunch. The bunch travels from left to right. The timing of the modulation is determined by the preceding electron bunch and it is reproducible from event to event.
Edda Gschwendtner, the AWAKE project leader at CERN, looks to the future with optimism: “The ultimate success of the wakefield technology developed by AWAKE rests on the feasibility of seeding the proton bunch self-modulation. With this milestone now achieved, the collaboration is ready to tackle our next challenges, starting with the commissioning of a new plasma source”. This source, which is being developed by the Max Planck Institute in Munich, Germany, will generate a plasma with two regions of different density (and, therefore, of different temperature), which will further increase the overall acceleration gradient with respect to that achieved so far. The introduction of a new plasma source is only one aspect of the rich programme of studies to be performed during AWAKE’s second physics run.
CERN’s Long Shutdown 3 will see the dismantling of the last remaining components of the CNGS facility. AWAKE plans to make the most of this opportunity, using the freed space for the next phases of the experiment. These phases will focus on accelerating electrons to high energy while preserving the beam quality, a prerequisite for future applications in particle physics. In parallel, the collaboration will continue to develop scalable plasma source technologies, such as discharge and helicon plasma cells, which are key to increasing the final energy reach. Once these technologies have been validated, and controlled electron acceleration has been demonstrated, it will open the door to future high-energy applications, such as fixed-target experiments searching for dark matter.
thortala Mon, 07/18/2022 - 11:24 Byline Thomas Hortala Publication Date Mon, 07/18/2022 - 11:22The VELO was installed at the LHCb experiment in May 2022, just in time for the start of the third LHC run, on 5 July, marking the end of 15 years of development and construction.
The pixel detector, with its millions of microscopic pixels, each measuring 55 x 55 micrometres, can recreate particles’ trajectories at an unprecedented speed of 40 million times per second and is located only 3 millimetres from the LHCb collision point. This frenetic rate will make it possible to obtain a complete picture of the collisions in the LHC.
Weighing 800 kilograms, the VELO was installed by the LHCb team with the utmost care to avoid damaging its fragile sensors. It was lowered 100 metres down through the experiment’s shaft before being inserted right up close to the collision point.
To find out more about the VELO’s installation, watch the interview with LHCb physicist Paula Collins.
(Video: CERN)thortala Tue, 07/05/2022 - 15:51 Byline Reema Altamimi Publication Date Tue, 07/05/2022 - 15:41
The Hellenic Society for the Study of High Energy Physics (HeSSHEP) promotes the scientific work of the Greek scientists, informs the general public and the Greek state on matters concerning the subject of High Energy Physics, organizes an workshop and conferences.
