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Investigation of Low-Energy Particle Remnants in High-Energy Collisions at the LHC with a Skipper-CCD detector
Authors:
Brenda A. Cervantes-Vergara,
Santiago E. Perez,
Nicola Bacchetta,
Nuria Castello-Mor,
Juan Estrada,
Marcos Fernandez Garcia,
Petra Merkel,
Maria Perez Martinez,
Dario Rodrigues,
Javier Tiffenberg,
Rocio Vilar Cortabitarte
Abstract:
We deployed MOSKITA $\sim$33 m away from the CMS collision point, the first skipper-CCD detector probing low-energy particles produced in high-energy collisions at the Large Hadron Collider (LHC). In this work, we search for beam-related events using data collected in 2024 during beam-on and beam-off periods. The dataset corresponds to integrated luminosities of 113.3 fb$^{-1}$ and 1.54 nb$^{-1}$…
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We deployed MOSKITA $\sim$33 m away from the CMS collision point, the first skipper-CCD detector probing low-energy particles produced in high-energy collisions at the Large Hadron Collider (LHC). In this work, we search for beam-related events using data collected in 2024 during beam-on and beam-off periods. The dataset corresponds to integrated luminosities of 113.3 fb$^{-1}$ and 1.54 nb$^{-1}$ for the proton-proton and Pb-Pb collision periods, respectively. We report observed event rates in a model-independent framework across two ionization regions: $\leq20e^-$ and $>20e^-$. For the low-energy region, we perform a likelihood analysis to test the null hypothesis of no beam-correlated signal. We found no significant correlation during proton-proton and Pb-Pb collisions. For the high-energy region, we present the energy spectra for both collision periods and compare event rates for images with and without luminosity. We observe a slight increase in the event rate following the Pb-Pb collisions, coinciding with a rise in the single-electron rate, which will be investigated in future work. Using the low-energy proton-proton results, we place 95% C.L. constraints on the mass-millicharge parameter space of millicharged particles. Overall, the results in this work demonstrate the viability of skipper-CCD technology to explore new physics at high-energy colliders and motivate future searches with more massive detectors.
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Submitted 8 August, 2025;
originally announced August 2025.
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Report of the Instrumentation Frontier Working Group for Snowmass 2021
Authors:
Phillip S. Barbeau,
Petra Merkel,
Jinlong Zhang,
Darin Acosta,
Anthony A. Affolder,
Artur Apresyan,
Marina Artuso,
Vallary Bhopatkar,
Stephen Butalla,
Gabriella A. Carini,
Thomas Cecil,
Amy Connolly,
C. Eric Dahl,
Allison Deiana,
Katherine Dunne,
Carlos O. Escobar,
Juan Estrada,
Farah Fahim,
James E. Fast,
Maurice Garcia-Sciveres,
Roxanne Guenette,
Michael T. Hedges,
Kent Irwin,
Albrecht Karle,
Wes Ketchum
, et al. (20 additional authors not shown)
Abstract:
Detector instrumentation is at the heart of scientific discoveries. Cutting edge technologies enable US particle physics to play a leading role worldwide. This report summarizes the current status of instrumentation for High Energy Physics (HEP), the challenges and needs of future experiments and indicates high priority research areas. The Snowmass Instrumentation Frontier studies detector technol…
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Detector instrumentation is at the heart of scientific discoveries. Cutting edge technologies enable US particle physics to play a leading role worldwide. This report summarizes the current status of instrumentation for High Energy Physics (HEP), the challenges and needs of future experiments and indicates high priority research areas. The Snowmass Instrumentation Frontier studies detector technologies and Research and Development (R&D) needed for future experiments in collider physics, neutrino physics, rare and precision physics and at the cosmic frontier. It is divided into more or less diagonal areas with some overlap among a few of them. We lay out five high-level key messages that are geared towards ensuring the health and competitiveness of the US detector instrumentation community, and thus the entire particle physics landscape.
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Submitted 3 November, 2022; v1 submitted 28 September, 2022;
originally announced September 2022.
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Solid State Detectors and Tracking for Snowmass
Authors:
A. Affolder,
A. Apresyan,
S. Worm,
M. Albrow,
D. Ally,
D. Ambrose,
E. Anderssen,
N. Apadula,
P. Asenov,
W. Armstrong,
M. Artuso,
A. Barbier,
P. Barletta,
L. Bauerdick,
D. Berry,
M. Bomben,
M. Boscardin,
J. Brau,
W. Brooks,
M. Breidenbach,
J. Buckley,
V. Cairo,
R. Caputo,
L. Carpenter,
M. Centis-Vignali
, et al. (110 additional authors not shown)
Abstract:
Tracking detectors are of vital importance for collider-based high energy physics (HEP) experiments. The primary purpose of tracking detectors is the precise reconstruction of charged particle trajectories and the reconstruction of secondary vertices. The performance requirements from the community posed by the future collider experiments require an evolution of tracking systems, necessitating the…
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Tracking detectors are of vital importance for collider-based high energy physics (HEP) experiments. The primary purpose of tracking detectors is the precise reconstruction of charged particle trajectories and the reconstruction of secondary vertices. The performance requirements from the community posed by the future collider experiments require an evolution of tracking systems, necessitating the development of new techniques, materials and technologies in order to fully exploit their physics potential. In this article we summarize the discussions and conclusions of the 2022 Snowmass Instrumentation Frontier subgroup on Solid State and Tracking Detectors (Snowmass IF03).
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Submitted 19 October, 2022; v1 submitted 8 September, 2022;
originally announced September 2022.
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Climate impacts of particle physics
Authors:
Kenneth Bloom,
Veronique Boisvert,
Daniel Britzger,
Micah Buuck,
Astrid Eichhorn,
Michael Headley,
Kristin Lohwasser,
Petra Merkel
Abstract:
The pursuit of particle physics requires a stable and prosperous society. Today, our society is increasingly threatened by global climate change. Human-influenced climate change has already impacted weather patterns, and global warming will only increase unless deep reductions in emissions of CO$_2$ and other greenhouse gases are achieved. Current and future activities in particle physics need to…
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The pursuit of particle physics requires a stable and prosperous society. Today, our society is increasingly threatened by global climate change. Human-influenced climate change has already impacted weather patterns, and global warming will only increase unless deep reductions in emissions of CO$_2$ and other greenhouse gases are achieved. Current and future activities in particle physics need to be considered in this context, either on the moral ground that we have a responsibility to leave a habitable planet to future generations, or on the more practical ground that, because of their scale, particle physics projects and activities will be under scrutiny for their impact on the climate. In this white paper for the U.S. Particle Physics Community Planning Exercise ("Snowmass"), we examine several contexts in which the practice of particle physics has impacts on the climate. These include the construction of facilities, the design and operation of particle detectors, the use of large-scale computing, and the research activities of scientists. We offer recommendations on establishing climate-aware practices in particle physics, with the goal of reducing our impact on the climate. We invite members of the community to show their support for a sustainable particle physics field (https://indico.fnal.gov/event/53795/).
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Submitted 23 August, 2022; v1 submitted 23 March, 2022;
originally announced March 2022.
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Test Beam and Irradiation Facilities
Authors:
M. Hartz,
P. Merkel,
E. Niner,
E. Prebys,
N. Toro
Abstract:
Progress in particle physics depends on a multitude of unique facilities and capabilities that enable to advance detector technologies. Among others, key facilities involve test beams and irradiation facilities, which allow users to test the performance and lifetime of their detectors under realistic conditions. Test beam facilities are particularly important for collider and neutrino detector app…
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Progress in particle physics depends on a multitude of unique facilities and capabilities that enable to advance detector technologies. Among others, key facilities involve test beams and irradiation facilities, which allow users to test the performance and lifetime of their detectors under realistic conditions. Test beam facilities are particularly important for collider and neutrino detector applications, while irradiation facilities are crucial for collider as well as some space-based astro particle detectors. This contributed Snowmass paper aims to summarize existing test beam and irradiation facilities as well as develop the need and proposals for future facilities.
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Submitted 15 March, 2022;
originally announced March 2022.
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Higgs-Energy LEptoN (HELEN) Collider based on advanced superconducting radio frequency technology
Authors:
S. Belomestnykh,
P. C. Bhat,
A. Grassellino,
M. Checchin,
D. Denisov,
R. L. Geng,
S. Jindariani,
M. Liepe,
M. Martinello,
P. Merkel,
S. Nagaitsev,
H. Padamsee,
S. Posen,
R. A. Rimmer,
A. Romanenko,
V. Shiltsev,
A. Valishev,
V. Yakovlev
Abstract:
This Snowmass 2021 contributed paper discusses a Higgs-Energy LEptoN (HELEN) $e^+e^-$ linear collider based on advances superconducting radio frequency technology. The proposed collider offers cost and AC power savings, smaller footprint (relative to the ILC), and could be built at Fermilab with an Interaction Region within the site boundaries. After the initial physics run at 250 GeV, the collide…
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This Snowmass 2021 contributed paper discusses a Higgs-Energy LEptoN (HELEN) $e^+e^-$ linear collider based on advances superconducting radio frequency technology. The proposed collider offers cost and AC power savings, smaller footprint (relative to the ILC), and could be built at Fermilab with an Interaction Region within the site boundaries. After the initial physics run at 250 GeV, the collider could be upgraded either to higher luminosity or to higher (up to 500 GeV) energies. If the ILC could not be realized in Japan in a timely fashion, the HELEN collider would be a viable option to build a Higgs factory in the U.S.
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Submitted 15 March, 2022;
originally announced March 2022.
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Future Collider Options for the US
Authors:
P. C. Bhat,
S. Jindariani,
G. Ambrosio,
G. Apollinari,
S. Belomestnykh,
A. Bross,
J. Butler,
A. Canepa,
D. Elvira,
P. Fox,
Z. Gecse,
E. Gianfelice-Wendt,
P. Merkel,
S. Nagaitsev,
D. Neuffer,
H. Piekarz,
S. Posen,
T. Sen,
V. Shiltsev,
N. Solyak,
D. Stratakis,
M. Syphers,
G. Velev,
V. Yakovlev,
K. Yonehara
, et al. (1 additional authors not shown)
Abstract:
The United States has a rich history in high energy particle accelerators and colliders -- both lepton and hadron machines, which have enabled several major discoveries in elementary particle physics. To ensure continued progress in the field, U.S. leadership as a key partner in building next generation collider facilities abroad is essential; also critically important is the exploring of options…
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The United States has a rich history in high energy particle accelerators and colliders -- both lepton and hadron machines, which have enabled several major discoveries in elementary particle physics. To ensure continued progress in the field, U.S. leadership as a key partner in building next generation collider facilities abroad is essential; also critically important is the exploring of options to host a future collider in the U.S. The "Snowmass" study and the subsequent Particle Physics Project Prioritization Panel (P5) process provide the timely opportunity to develop strategies for both. What we do now will shape the future of our field and whether the U.S. will remain a world leader in these areas. In this white paper, we briefly discuss the US engagement in proposed collider projects abroad and describe future collider options for the U.S. We also call for initiating an integrated R\&D program for future colliders.
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Submitted 15 March, 2022;
originally announced March 2022.
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The International Linear Collider: Report to Snowmass 2021
Authors:
Alexander Aryshev,
Ties Behnke,
Mikael Berggren,
James Brau,
Nathaniel Craig,
Ayres Freitas,
Frank Gaede,
Spencer Gessner,
Stefania Gori,
Christophe Grojean,
Sven Heinemeyer,
Daniel Jeans,
Katja Kruger,
Benno List,
Jenny List,
Zhen Liu,
Shinichiro Michizono,
David W. Miller,
Ian Moult,
Hitoshi Murayama,
Tatsuya Nakada,
Emilio Nanni,
Mihoko Nojiri,
Hasan Padamsee,
Maxim Perelstein
, et al. (487 additional authors not shown)
Abstract:
The International Linear Collider (ILC) is on the table now as a new global energy-frontier accelerator laboratory taking data in the 2030s. The ILC addresses key questions for our current understanding of particle physics. It is based on a proven accelerator technology. Its experiments will challenge the Standard Model of particle physics and will provide a new window to look beyond it. This docu…
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The International Linear Collider (ILC) is on the table now as a new global energy-frontier accelerator laboratory taking data in the 2030s. The ILC addresses key questions for our current understanding of particle physics. It is based on a proven accelerator technology. Its experiments will challenge the Standard Model of particle physics and will provide a new window to look beyond it. This document brings the story of the ILC up to date, emphasizing its strong physics motivation, its readiness for construction, and the opportunity it presents to the US and the global particle physics community.
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Submitted 16 January, 2023; v1 submitted 14 March, 2022;
originally announced March 2022.
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Physics Opportunities for the Fermilab Booster Replacement
Authors:
John Arrington,
Joshua Barrow,
Brian Batell,
Robert Bernstein,
Nikita Blinov,
S. J. Brice,
Ray Culbertson,
Patrick deNiverville,
Vito Di Benedetto,
Jeff Eldred,
Angela Fava,
Laura Fields,
Alex Friedland,
Andrei Gaponenko,
Corrado Gatto,
Stefania Gori,
Roni Harnik,
Richard J. Hill,
Daniel M. Kaplan,
Kevin J. Kelly,
Mandy Kiburg,
Tom Kobilarcik,
Gordan Krnjaic,
Gabriel Lee,
B. R. Littlejohn
, et al. (27 additional authors not shown)
Abstract:
This white paper presents opportunities afforded by the Fermilab Booster Replacement and its various options. Its goal is to inform the design process of the Booster Replacement about the accelerator needs of the various options, allowing the design to be versatile and enable, or leave the door open to, as many options as possible. The physics themes covered by the paper include searches for dark…
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This white paper presents opportunities afforded by the Fermilab Booster Replacement and its various options. Its goal is to inform the design process of the Booster Replacement about the accelerator needs of the various options, allowing the design to be versatile and enable, or leave the door open to, as many options as possible. The physics themes covered by the paper include searches for dark sectors and new opportunities with muons.
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Submitted 8 March, 2022;
originally announced March 2022.
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The JOREK non-linear extended MHD code and applications to large-scale instabilities and their control in magnetically confined fusion plasmas
Authors:
M Hoelzl,
GTA Huijsmans,
SJP Pamela,
M Becoulet,
E Nardon,
FJ Artola,
B Nkonga,
CV Atanasiu,
V Bandaru,
A Bhole,
D Bonfiglio,
A Cathey,
O Czarny,
A Dvornova,
T Feher,
A Fil,
E Franck,
S Futatani,
M Gruca,
H Guillard,
JW Haverkort,
I Holod,
D Hu,
SK Kim,
SQ Korving
, et al. (28 additional authors not shown)
Abstract:
JOREK is a massively parallel fully implicit non-linear extended MHD code for realistic tokamak X-point plasmas. It has become a widely used versatile code for studying large-scale plasma instabilities and their control developed in an international community. This article gives a comprehensive overview of the physics models implemented, numerical methods applied for solving the equations and phys…
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JOREK is a massively parallel fully implicit non-linear extended MHD code for realistic tokamak X-point plasmas. It has become a widely used versatile code for studying large-scale plasma instabilities and their control developed in an international community. This article gives a comprehensive overview of the physics models implemented, numerical methods applied for solving the equations and physics studies performed with the code. A dedicated section highlights some of the verification work done for the code. A hierarchy of different physics models is available including a free boundary and resistive wall extension and hybrid kinetic-fluid models. The code allows for flux-surface aligned iso-parametric finite element grids in single and double X-point plasmas which can be extended to the true physical walls and uses a robust fully implicit time stepping. Particular focus is laid on plasma edge and scrape-off layer (SOL) physics as well as disruption related phenomena. Among the key results obtained with JOREK regarding plasma edge and SOL, are deep insights into the dynamics of edge localized modes (ELMs), ELM cycles, and ELM control by resonant magnetic perturbations, pellet injection, as well as by vertical magnetic kicks. Also ELM free regimes, detachment physics, the generation and transport of impurities during an ELM, and electrostatic turbulence in the pedestal region are investigated. Regarding disruptions, the focus is on the dynamics of the thermal quench and current quench triggered by massive gas injection (MGI) and shattered pellet injection (SPI), runaway electron (RE) dynamics as well as the RE interaction with MHD modes, and vertical displacement events (VDEs). Also the seeding and suppression of tearing modes (TMs), the dynamics of naturally occurring thermal quenches triggered by locked modes, and radiative collapses are being studied.
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Submitted 21 April, 2021; v1 submitted 18 November, 2020;
originally announced November 2020.
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New Technologies for Discovery
Authors:
Z. Ahmed,
A. Apresyan,
M. Artuso,
P. Barry,
E. Bielejec,
F. Blaszczyk,
T. Bose,
D. Braga,
S. A. Charlebois,
A. Chatterjee,
A. Chavarria,
H. -M. Cho,
S. Dalla Torre,
M. Demarteau,
D. Denisov,
M. Diefenthaler,
A. Dragone,
F. Fahim,
C. Gee,
S. Habib,
G. Haller,
J. Hogan,
B. J. P. Jones,
M. Garcia-Sciveres,
G. Giacomini
, et al. (58 additional authors not shown)
Abstract:
For the field of high energy physics to continue to have a bright future, priority within the field must be given to investments in the development of both evolutionary and transformational detector development that is coordinated across the national laboratories and with the university community, international partners and other disciplines. While the fundamental science questions addressed by hi…
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For the field of high energy physics to continue to have a bright future, priority within the field must be given to investments in the development of both evolutionary and transformational detector development that is coordinated across the national laboratories and with the university community, international partners and other disciplines. While the fundamental science questions addressed by high energy physics have never been more compelling, there is acute awareness of the challenging budgetary and technical constraints when scaling current technologies. Furthermore, many technologies are reaching their sensitivity limit and new approaches need to be developed to overcome the currently irreducible technological challenges. This situation is unfolding against a backdrop of declining funding for instrumentation, both at the national laboratories and in particular at the universities. This trend has to be reversed for the country to continue to play a leadership role in particle physics, especially in this most promising era of imminent new discoveries that could finally break the hugely successful, but limited, Standard Model of fundamental particle interactions. In this challenging environment it is essential that the community invest anew in instrumentation and optimize the use of the available resources to develop new innovative, cost-effective instrumentation, as this is our best hope to successfully accomplish the mission of high energy physics. This report summarizes the current status of instrumentation for high energy physics, the challenges and needs of future experiments and indicates high priority research areas.
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Submitted 10 August, 2019; v1 submitted 31 July, 2019;
originally announced August 2019.
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A boron-coated CCD camera for direct detection of Ultracold Neutrons (UCN)
Authors:
K. Kuk,
C. Cude-Woods,
C. R. Chavez,
J. H. Choi,
J. Estrada,
M. Hoffbauer,
M. Makela,
P. Merkel,
C. L. Morris,
E. Ramberg,
Z. Wang,
T. Bailey,
M. Blatnik,
E. R. Adamek,
L. J. Broussard,
M. A. -P. Brown,
N. B. Callahan,
S. M. Clayton,
S. A. Currie,
X. Ding,
D. Dinger,
B. Filippone,
E. M. Fries,
P. Geltenbort,
E. George
, et al. (26 additional authors not shown)
Abstract:
A new boron-coated CCD camera is described for direct detection of ultracold neutrons (UCN) through the capture reactions $^{10}$B (n,$α$0$γ$)$^7$Li (6%) and $^{10}$B(n,$α$1$γ$)$^7$Li (94%). The experiments, which extend earlier works using a boron-coated ZnS:Ag scintillator, are based on direct detections of the neutron-capture byproducts in silicon. The high position resolution, energy resolutio…
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A new boron-coated CCD camera is described for direct detection of ultracold neutrons (UCN) through the capture reactions $^{10}$B (n,$α$0$γ$)$^7$Li (6%) and $^{10}$B(n,$α$1$γ$)$^7$Li (94%). The experiments, which extend earlier works using a boron-coated ZnS:Ag scintillator, are based on direct detections of the neutron-capture byproducts in silicon. The high position resolution, energy resolution and particle ID performance of a scientific CCD allows for observation and identification of all the byproducts $α$, $^7$Li and $γ$ (electron recoils). A signal-to-noise improvement on the order of 10$^4$ over the indirect method has been achieved. Sub-pixel position resolution of a few microns is demonstrated. The technology can also be used to build UCN detectors with an area on the order of 1 m$^2$. The combination of micrometer scale spatial resolution, few electrons ionization thresholds and large area paves the way to new research avenues including quantum physics of UCN and high-resolution neutron imaging and spectroscopy.
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Submitted 28 February, 2019;
originally announced March 2019.
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Quantum Sensing for High Energy Physics
Authors:
Zeeshan Ahmed,
Yuri Alexeev,
Giorgio Apollinari,
Asimina Arvanitaki,
David Awschalom,
Karl K. Berggren,
Karl Van Bibber,
Przemyslaw Bienias,
Geoffrey Bodwin,
Malcolm Boshier,
Daniel Bowring,
Davide Braga,
Karen Byrum,
Gustavo Cancelo,
Gianpaolo Carosi,
Tom Cecil,
Clarence Chang,
Mattia Checchin,
Sergei Chekanov,
Aaron Chou,
Aashish Clerk,
Ian Cloet,
Michael Crisler,
Marcel Demarteau,
Ranjan Dharmapalan
, et al. (91 additional authors not shown)
Abstract:
Report of the first workshop to identify approaches and techniques in the domain of quantum sensing that can be utilized by future High Energy Physics applications to further the scientific goals of High Energy Physics.
Report of the first workshop to identify approaches and techniques in the domain of quantum sensing that can be utilized by future High Energy Physics applications to further the scientific goals of High Energy Physics.
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Submitted 29 March, 2018;
originally announced March 2018.
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Test Beam Performance Measurements for the Phase I Upgrade of the CMS Pixel Detector
Authors:
M. Dragicevic,
M. Friedl,
J. Hrubec,
H. Steininger,
A. Gädda,
J. Härkönen,
T. Lampén,
P. Luukka,
T. Peltola,
E. Tuominen,
E. Tuovinen,
A. Winkler,
P. Eerola,
T. Tuuva,
G. Baulieu,
G. Boudoul,
L. Caponetto,
C. Combaret,
D. Contardo,
T. Dupasquier,
G. Gallbit,
N. Lumb,
L. Mirabito,
S. Perries,
M. Vander Donckt
, et al. (462 additional authors not shown)
Abstract:
A new pixel detector for the CMS experiment was built in order to cope with the instantaneous luminosities anticipated for the Phase~I Upgrade of the LHC. The new CMS pixel detector provides four-hit tracking with a reduced material budget as well as new cooling and powering schemes. A new front-end readout chip mitigates buffering and bandwidth limitations, and allows operation at low comparator…
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A new pixel detector for the CMS experiment was built in order to cope with the instantaneous luminosities anticipated for the Phase~I Upgrade of the LHC. The new CMS pixel detector provides four-hit tracking with a reduced material budget as well as new cooling and powering schemes. A new front-end readout chip mitigates buffering and bandwidth limitations, and allows operation at low comparator thresholds. In this paper, comprehensive test beam studies are presented, which have been conducted to verify the design and to quantify the performance of the new detector assemblies in terms of tracking efficiency and spatial resolution. Under optimal conditions, the tracking efficiency is $99.95\pm0.05\,\%$, while the intrinsic spatial resolutions are $4.80\pm0.25\,μ\mathrm{m}$ and $7.99\pm0.21\,μ\mathrm{m}$ along the $100\,μ\mathrm{m}$ and $150\,μ\mathrm{m}$ pixel pitch, respectively. The findings are compared to a detailed Monte Carlo simulation of the pixel detector and good agreement is found.
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Submitted 1 June, 2017;
originally announced June 2017.
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Linear MHD stability studies with the STARWALL code
Authors:
P. Merkel,
E. Strumberger
Abstract:
The STARWALL/CAS3D/OPTIM code package is a powerful tool to study the linear MHD stability of 3D, ideal equilibria in the presence of multiply-connected ideal and/or resistive conducting structures, and their feedback stabilization by external currents. Robust feedback stabilization of resistive wall modes can be modelled with the OPTIM code. Resistive MHD studies are possible combining STARWALL w…
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The STARWALL/CAS3D/OPTIM code package is a powerful tool to study the linear MHD stability of 3D, ideal equilibria in the presence of multiply-connected ideal and/or resistive conducting structures, and their feedback stabilization by external currents. Robust feedback stabilization of resistive wall modes can be modelled with the OPTIM code. Resistive MHD studies are possible combining STARWALL with the linear, resistive 2D CASTOR code as well as nonlinear MHD simulations combining STARWALL with the JOREK code.
In the present paper, a detailed description of the STARWALL code is given and some of its applications are presented to demonstrate the methods used. Conducting structures are treated in the thin wall approximation and depending on their complexity they are discretized by a spectral method or by triangular finite elements. As an example, a configuration is considered consisting of an ideal plasma surrounded by a vacuum domain containing a resistive wall and bounded by an external wall. Ideal linear MHD modes and resistive wall modes in the presence of multiply-connected walls are studied. In order to treat the vertical mode self-consistently the STARWALL code has been completed by adding the so-called Luest-Martensen term generated by a constant normal displacement of the plasma.
The appendix contains the computation of the 2D Fourier transform of singular inductance integrals, and the derivation of an asymptotic expansion for large Fourier harmonics.
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Submitted 20 August, 2015;
originally announced August 2015.
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Trapping in irradiated p-on-n silicon sensors at fluences anticipated at the HL-LHC outer tracker
Authors:
W. Adam,
T. Bergauer,
M. Dragicevic,
M. Friedl,
R. Fruehwirth,
M. Hoch,
J. Hrubec,
M. Krammer,
W. Treberspurg,
W. Waltenberger,
S. Alderweireldt,
W. Beaumont,
X. Janssen,
S. Luyckx,
P. Van Mechelen,
N. Van Remortel,
A. Van Spilbeeck,
P. Barria,
C. Caillol,
B. Clerbaux,
G. De Lentdecker,
D. Dobur,
L. Favart,
A. Grebenyuk,
Th. Lenzi
, et al. (663 additional authors not shown)
Abstract:
The degradation of signal in silicon sensors is studied under conditions expected at the CERN High-Luminosity LHC. 200 $μ$m thick n-type silicon sensors are irradiated with protons of different energies to fluences of up to $3 \cdot 10^{15}$ neq/cm$^2$. Pulsed red laser light with a wavelength of 672 nm is used to generate electron-hole pairs in the sensors. The induced signals are used to determi…
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The degradation of signal in silicon sensors is studied under conditions expected at the CERN High-Luminosity LHC. 200 $μ$m thick n-type silicon sensors are irradiated with protons of different energies to fluences of up to $3 \cdot 10^{15}$ neq/cm$^2$. Pulsed red laser light with a wavelength of 672 nm is used to generate electron-hole pairs in the sensors. The induced signals are used to determine the charge collection efficiencies separately for electrons and holes drifting through the sensor. The effective trapping rates are extracted by comparing the results to simulation. The electric field is simulated using Synopsys device simulation assuming two effective defects. The generation and drift of charge carriers are simulated in an independent simulation based on PixelAV. The effective trapping rates are determined from the measured charge collection efficiencies and the simulated and measured time-resolved current pulses are compared. The effective trapping rates determined for both electrons and holes are about 50% smaller than those obtained using standard extrapolations of studies at low fluences and suggests an improved tracker performance over initial expectations.
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Submitted 7 May, 2015;
originally announced May 2015.
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Non-linear Simulations of MHD Instabilities in Tokamaks Including Eddy Current Effects and Perspectives for the Extension to Halo Currents
Authors:
M. Hoelzl,
G. T. A. Huijsmans,
P. Merkel,
C. Atanasiu,
K. Lackner,
E. Nardon,
K. Aleynikova,
F. Liu,
E. Strumberger,
R. McAdams,
I. Chapman,
A. Fil
Abstract:
The dynamics of large scale plasma instabilities can strongly be influenced by the mutual interaction with currents flowing in conducting vessel structures. Especially eddy currents caused by time-varying magnetic perturbations and halo currents flowing directly from the plasma into the walls are important. The relevance of a resistive wall model is directly evident for Resistive Wall Modes (RWMs)…
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The dynamics of large scale plasma instabilities can strongly be influenced by the mutual interaction with currents flowing in conducting vessel structures. Especially eddy currents caused by time-varying magnetic perturbations and halo currents flowing directly from the plasma into the walls are important. The relevance of a resistive wall model is directly evident for Resistive Wall Modes (RWMs) or Vertical Displacement Events (VDEs). However, also the linear and non-linear properties of most other large-scale instabilities may be influenced significantly by the interaction with currents in conducting structures near the plasma. The understanding of halo currents arising during disruptions and VDEs, which are a serious concern for ITER as they may lead to strong asymmetric forces on vessel structures, could also benefit strongly from these non-linear modeling capabilities. Modeling the plasma dynamics and its interaction with wall currents requires solving the magneto-hydrodynamic (MHD) equations in realistic toroidal X-point geometry consistently coupled with a model for the vacuum region and the resistive conducting structures. With this in mind, the non-linear finite element MHD code JOREK has been coupled with the resistive wall code STARWALL, which allows to include the effects of eddy currents in 3D conducting structures in non-linear MHD simulations. This article summarizes the capabilities of the coupled JOREK-STARWALL system and presents benchmark results as well as first applications to non-linear simulations of RWMs, VDEs, disruptions triggered by massive gas injection, and Quiescent H-Mode. As an outlook, the perspectives for extending the model to halo currents are described.
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Submitted 23 September, 2014; v1 submitted 27 August, 2014;
originally announced August 2014.
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Operational experience, improvements, and performance of the CDF Run II silicon vertex detector
Authors:
T. Aaltonen,
S. Behari,
A. Boveia,
B. Brau,
G. Bolla,
D. Bortoletto,
C. Calancha,
S. Carron,
S. Cihangir,
M. Corbo,
D. Clark,
B. Di Ruzza,
R. Eusebi,
J. P. Fernandez,
J. C. Freeman,
J. E. Garcia,
M. Garcia-Sciveres,
D. Glenzinski,
O. Gonzalez,
S. Grinstein,
M. Hartz,
M. Herndon,
C. Hill,
A. Hocker,
U. Husemann
, et al. (35 additional authors not shown)
Abstract:
The Collider Detector at Fermilab (CDF) pursues a broad physics program at Fermilab's Tevatron collider. Between Run II commissioning in early 2001 and the end of operations in September 2011, the Tevatron delivered 12 fb-1 of integrated luminosity of p-pbar collisions at sqrt(s)=1.96 TeV. Many physics analyses undertaken by CDF require heavy flavor tagging with large charged particle tracking acc…
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The Collider Detector at Fermilab (CDF) pursues a broad physics program at Fermilab's Tevatron collider. Between Run II commissioning in early 2001 and the end of operations in September 2011, the Tevatron delivered 12 fb-1 of integrated luminosity of p-pbar collisions at sqrt(s)=1.96 TeV. Many physics analyses undertaken by CDF require heavy flavor tagging with large charged particle tracking acceptance. To realize these goals, in 2001 CDF installed eight layers of silicon microstrip detectors around its interaction region. These detectors were designed for 2--5 years of operation, radiation doses up to 2 Mrad (0.02 Gy), and were expected to be replaced in 2004. The sensors were not replaced, and the Tevatron run was extended for several years beyond its design, exposing the sensors and electronics to much higher radiation doses than anticipated. In this paper we describe the operational challenges encountered over the past 10 years of running the CDF silicon detectors, the preventive measures undertaken, and the improvements made along the way to ensure their optimal performance for collecting high quality physics data. In addition, we describe the quantities and methods used to monitor radiation damage in the sensors for optimal performance and summarize the detector performance quantities important to CDF's physics program, including vertex resolution, heavy flavor tagging, and silicon vertex trigger performance.
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Submitted 3 October, 2013; v1 submitted 14 January, 2013;
originally announced January 2013.
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Coupling JOREK and STARWALL for Non-linear Resistive-wall Simulations
Authors:
M. Hoelzl,
P. Merkel,
G. T. A. Huysmans,
E. Nardon,
E. Strumberger,
R. McAdams,
I. Chapman,
S. Guenter,
K. Lackner
Abstract:
The implementation of a resistive-wall extension to the non-linear MHD-code JOREK via a coupling to the vacuum-field code STARWALL is presented along with first applications and benchmark results. Also, non-linear saturation in the presence of a resistive wall is demonstrated. After completion of the ongoing verification process, this code extension will allow to perform non-linear simulations of…
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The implementation of a resistive-wall extension to the non-linear MHD-code JOREK via a coupling to the vacuum-field code STARWALL is presented along with first applications and benchmark results. Also, non-linear saturation in the presence of a resistive wall is demonstrated. After completion of the ongoing verification process, this code extension will allow to perform non-linear simulations of MHD instabilities in the presence of three-dimensional resistive walls with holes for limited and X-point plasmas.
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Submitted 4 October, 2012; v1 submitted 13 June, 2012;
originally announced June 2012.