Resistivity Characterization of Molybdenum-Coated Graphite-Based Substrates for High-Luminosity LHC Collimators

The High-Luminosity Large Hadron Collider (HL-LHC) project aims at extending the operability of the LHC by another decade and increasing by more than a factor of ten the integrated luminosity that the LHC will have collected by the end of Run 3. This will require doubling the beam intensity and reducing the transverse beam size compared to those of the LHC design. The higher beam brightness poses new challenges for machine safety, due to the large energy of 700 MJ stored in the beams, and for beam stability, mainly due to the collimator contribution to the total LHC beam coupling impedance. A rich research program was therefore started to identify suitable materials and collimator designs, not only fulfilling impedance reduction requirements but also granting adequate beam-cleaning and robustness against failures. The use of thin molybdenum coatings on a molybdenum–graphite substrate has been identified as the most promising solution to meet both collimation and impedance requirements, and it is now the baseline choice of the HL-LHC project. In this work we present the main results of the coating characterization, in particular addressing the impact of coating microstructure on the electrical resistivity with different techniques, from Direct Current (DC) to GHz frequency range.

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Transverse beam stability with low-impedance collimators in the High-Luminosity Large Hadron Collider: Status and challenges

Physical Review Accelerators and Beams ◽

10.1103/physrevaccelbeams.23.034403 ◽

2020 ◽

Vol 23 (3) ◽

Cited By ~ 1

Author(s):

S. A. Antipov ◽

C. Accettura ◽

D. Amorim ◽

A. Bertarelli ◽

N. Biancacci ◽

...

Keyword(s):

Large Hadron Collider ◽

Hadron Collider ◽

High Luminosity ◽

Transverse Beam ◽

Beam Stability

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Characterization of semiconductor detectors and test beams with high-rate telescopes for the Tracker upgrade of the CMS experiment

10.12681/eadd/48370 ◽

2020 ◽

Author(s):

Πάτρικ Ασένοβ

Keyword(s):

Large Hadron Collider ◽

Compact Muon Solenoid ◽

Hadron Collider ◽

High Rate ◽

Semiconductor Detectors ◽

High Luminosity ◽

Cms Experiment

Για να αποκαλύψουν τα μυστήρια του σύμπαντος, οι φυσικοί υψηλών ενεργειών θα πρέπει να ενισχύσουν την ικανότητα για ανακαλύψεις του ισχυρότερου επιταχυντή συγκρούσεων σωματιδίων στον κόσμο. Ο Μεγάλος Αδρονικός Επιταχυντής Υψηλής Φωτεινότητας (High Luminosity Large Hadron Collider, HL-LHC) αποτελεί μια τρέχουσα αναβάθμιση του Μεγάλου Αδρονικού Επιταχυντή (Large Hadron Collider, LHC) η οποία στοχεύει στην αύξηση της φωτεινότητας του επιταχυντή κατά έναν παράγοντα 10, παρέχοντας καλύτερη δυνατότητα για παρατηρήσεις σπάνιων φαινομένων και για βελτιώσεις στατιστικά οριακών μετρήσεων. Προκειμένου να αντιμετωπίσει τις προκλήσεις της πρωτοφανούς φωτεινότητας πρωτονίων-πρωτονίων, η Συνεργασία Συμπαγές Μιονικό Σωληνοειδές (Compact Muon Solenoid, CMS) θα πρέπει να αντεπεξέλθει στη γήρανση του παρόντος ανιχνευτή και να προωθήσει τις μεθόδους που χρησιμοποιούνται για την απομόνωση και την ακριβή μέτρηση των προϊόντων των πιο σημαντικών συγκρούσεων. Για να προσδιοριστούν οι συνθήκες των πιο σημαντικών συμβάντων, είναι κρίσιμο να υπολογιστεί η ορμή των σωματιδίων παρακολουθώντας τις τροχιές τους δια μέσου του μαγνητικού πεδίου του ανιχνευτή. Όσο πιο καμπυλωτή η διαδρομή ενός σωματιδίου, τόσο λιγότερη ορμή είχε αρχικά. Οι διαδρομές φορτισμένων σωματιδίων καταγράφονται στο εσώτερο μέρος του ανιχνευτή CMS, του Τροχιοδεικτικού ανιχνευτή (Tracker), βρίσκοντας τις θέσεις των σωματιδίων σε διάφορα σημεία-κλειδιά. Ο Τροχιοδεικτικός ανιχνευτής είναι ικανός να ανακατασκευάσει τα μονοπάτια υψηλής ενέργειας μιονίων, ηλεκτρονίων και αδρονίων, καθώς και να καταχωρήσει τροχιές που προέρχονται από τη διάσπαση των βραχύβιων b κουαρκ που θα χρησιμοποιηθούν για τη μελέτη των διαφορών μεταξύ ύλης και αντιύλης. Η ακρίβεια της θέσης στον Τροχιοδεικτικό ανιχνευτή χρειάζεται να είναι της τάξης των 10 μικρομέτρων, ενώ το υλικό του να αντέχει σε δριμεία ακτινοβολία. Ο αναβαθμισμένος Τροχιοδεικτικός ανιχνευτής για την εποχή του HL-LHC θα κατασκευαστεί εξ ολοκλήρου από αισθητήρες πυριτίου, θα έχει βελτιωμένες δυνατότητες σκανδαλισμού και θα αποτελείται από δύο υπο-ανιχνευτές: έναν ανιχνευτή κορυφής κυψελίδων που θα καταλαμβάνει την εσωτερική περιοχή και έναν Εξωτερικό Τροχιοδεικτικό ανιχνευτή (Outer Tracker, OT) που θα αποτελείται από δομικές μονάδες μικρολωρίδων. Τα δισκίδια όλων των πρότυπων αισθητήρων μικρολωρίδων πυριτίου τύπου p που μελετήθηκαν στο πλαίσιο της Αναβάθμισης Φάσης-2 του Τροχιοδεικτικού ανιχνευτή του CMS περιείχαν μισοφέγγαρα (half-moons) με δομές δοκιμών. Ήταν απαραίτητο να εκτελεστούν ηλεκτρικός χαρακτηρισμός και δοκιμές ακτινοβόλησης στις δομές δοκιμής αποκομμένες από αυτά τα δισκίδια, προκειμένου να προσδιοριστούν η ποιότητα του υλικού και η συμπεριφορά των εξαρτημάτων που εμπεριέχονται στις δομές δοκιμής. Τα αποτελέσματα αυτών των δοκιμών αναλύονται στο παρόν έργο. Από την άλλη πλευρά, κατά τη διάρκεια της περιόδου έρευνας και ανάπτυξης οι δοκιμές υπό δέσμη είναι ένας ισχυρός τρόπος για να εξεταστεί η συμπεριφορά των αισθητήρων πυριτίου σε ρεαλιστικές συνθήκες. Τα τηλεσκόπια που χρησιμοποιούνταν στο παρελθόν διέθεταν ηλεκτρονικά ανάγνωσης αργά για τις ανάγκες του αναβαθμισμένου πειράματος CMS. Νέα τηλεσκόπια κυψελίδων σχεδιάστηκαν, κατασκευάστηκαν και τέθηκαν σε λειτουργία για δοκιμές με δέσμες υπό τον ονομαστικό ρυθμό του LHC με πρότυπες δομικές μονάδες για την Αναβάθμιση Φάσης-2 του Τροχιοδεικτικού ανιχνευτή του CMS. Οι πτυχές σχεδιασμού και λειτουργίας δύο τέτοιων τηλεσκοπίων υψηλού ρυθμού, καθώς και τα αποτελέσματα των πρώτων δοκιμών με δέσμες μαζί τους, περιγράφονται επίσης σε αυτή τη διατριβή.

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Assessment of the performance of High-Luminosity LHC operational scenarios: integrated luminosity and effective pile-up density

Canadian Journal of Physics ◽

10.1139/cjp-2018-0291 ◽

2019 ◽

Vol 97 (5) ◽

pp. 498-508 ◽

Cited By ~ 2

Author(s):

L. Medina ◽

R. Tomás ◽

G. Arduini ◽

M. Napsuciale

Keyword(s):

Hadron Collider ◽

High Luminosity ◽

Reduced Cross Section ◽

Proton Proton ◽

Density Control ◽

Pile Up ◽

Alternative Scenarios ◽

New Perspective ◽

The Impact ◽

Integrated Luminosity

The High-Luminosity Large Hadron Collider (HL-LHC) experiments will operate at unprecedented levels of event pile-up from proton–proton collisions at 14 TeV centre-of-mass energy. In this paper, we study the performance of the baseline and a series of alternative scenarios in terms of the delivered integrated luminosity and its quality (pile-up density). A new figure-of-merit is introduced, the effective pile-up density, a concept that reflects the expected detector efficiency in the reconstruction of event vertices for a given operational scenario, acting as a link between the machine and experimental sides. Alternative scenarios have been proposed either to improve the baseline performance or to provide operational schemes in the case of particular limitations. Simulations of the evolution of their optimum fills with the latest set of parameters of the HL-LHC are performed with β*-levelling, and the results are discussed in terms of both the integrated luminosity and the effective pile-up density. The crab kissing scheme, a proposed scenario for pile-up density control, is re-evaluated under this new perspective with updated beam and optics parameters. Estimates on the expected integrated luminosity due to the impact of crab cavity noise, full crab crossing, and reduced cross section for burn-off, are also presented.

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The Analyses of Learning Strategies in English as a Second Language: Theoretical Classification and Measurement Test

Voices of English Language Education Society ◽

10.29408/veles.v4i2.2199 ◽

2020 ◽

Vol 4 (2) ◽

pp. 118-129

Author(s):

Asti Gumartifa ◽

◽

Indah Windra Dwie Agustiani

Keyword(s):

Language Learning ◽

Learning Outcomes ◽

Learning Strategies ◽

Learning Process ◽

English Learners ◽

English Language ◽

Point Of View ◽

Effective Learning ◽

The Impact

Gaining English language learning effectively has been discussed all years long. Similarly, Learners have various troubles outcomes in the learning process. Creating a joyful and comfortable situation must be considered by learners. Thus, the implementation of effective learning strategies is certainly necessary for English learners. This descriptive study has two purposes: first, to introduce the classification and characterization of learning strategies such as; memory, cognitive, metacognitive, compensation, social, and affective strategies that are used by learners in the classroom and second, it provides some questionnaires item based on Strategy of Inventory for Language Learning (SILL) version 5.0 that can be used to examine the frequency of students’ learning strategies in the learning process. The summary of this study explains and discusses the researchers’ point of view on the impact of learning outcomes by learning strategies used. Finally, utilizing appropriate learning strategies are certainly beneficial for both teachers and learners to achieve the learning target effectively.

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Modulation of Gut Microbiota and Oxidative Status by β-Carotene in Late Pregnant Sows

Frontiers in Nutrition ◽

10.3389/fnut.2020.612875 ◽

2020 ◽

Vol 7 ◽

Author(s):

Xupeng Yuan ◽

Jiahao Yan ◽

Ruizhi Hu ◽

Yanli Li ◽

Ying Wang ◽

...

Keyword(s):

Gut Microbiota ◽

Dietary Supplementation ◽

Basal Diet ◽

Fecal Microbiota ◽

Control Group ◽

Metabolic Activities ◽

The Impact ◽

Positive Effect ◽

Β Carotene

Recent evidences suggest that gut microbiota plays an important role in regulating physiological and metabolic activities of pregnant sows, and β-carotene has a potentially positive effect on reproduction, but the impact of β-carotene on gut microbiota in pregnant sows remains unknown. This study aimed to explore the effect and mechanisms of β-carotene on the reproductive performance of sows from the aspect of gut microbiota. A total of 48 hybrid pregnant sows (Landrace × Yorkshire) with similar parity were randomly allocated into three groups (n = 16) and fed with a basal diet or a diet containing 30 or 90 mg/kg of β-carotene from day 90 of gestation until parturition. Dietary supplementation of 30 or 90 mg/kg β-carotene increased the number of live birth to 11.82 ± 1.54 and 12.29 ± 2.09, respectively, while the control group was 11.00 ± 1.41 (P = 0.201). Moreover, β-carotene increased significantly the serum nitric oxide (NO) level and glutathione peroxidase (GSH-Px) activity (P < 0.05). Characterization of fecal microbiota revealed that 90 mg/kg β-carotene increased the diversity of the gut flora (P < 0.05). In particular, β-carotene decreased the relative abundance of Firmicutes including Lachnospiraceae AC2044 group, Lachnospiraceae NK4B4 group and Ruminococcaceae UCG-008, but enriched Proteobacteria including Bilophila and Sutterella, and Actinobacteria including Corynebacterium and Corynebacterium 1 which are related to NO synthesis. These data demonstrated that dietary supplementation of β-carotene may increase antioxidant enzyme activity and NO, an important vasodilator to promote the neonatal blood circulation, through regulating gut microbiota in sows.

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Clonal approaches to understanding the impact of mutations on hematologic disease development

Blood ◽

10.1182/blood-2018-11-835405 ◽

2019 ◽

Vol 133 (13) ◽

pp. 1436-1445 ◽

Cited By ~ 6

Author(s):

Jyoti Nangalia ◽

Emily Mitchell ◽

Anthony R. Green

Keyword(s):

Somatic Mutations ◽

Clonal Selection ◽

Single Cells ◽

Driver Mutations ◽

Great Promise ◽

Tumor Evolution ◽

Disease Development ◽

Hematopoietic Tissue ◽

The Impact

Abstract Interrogation of hematopoietic tissue at the clonal level has a rich history spanning over 50 years, and has provided critical insights into both normal and malignant hematopoiesis. Characterization of chromosomes identified some of the first genetic links to cancer with the discovery of chromosomal translocations in association with many hematological neoplasms. The unique accessibility of hematopoietic tissue and the ability to clonally expand hematopoietic progenitors in vitro has provided fundamental insights into the cellular hierarchy of normal hematopoiesis, as well as the functional impact of driver mutations in disease. Transplantation assays in murine models have enabled cellular assessment of the functional consequences of somatic mutations in vivo. Most recently, next-generation sequencing–based assays have shown great promise in allowing multi-“omic” characterization of single cells. Here, we review how clonal approaches have advanced our understanding of disease development, focusing on the acquisition of somatic mutations, clonal selection, driver mutation cooperation, and tumor evolution.

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Exploring the Characteristics and Influencing Factors of Leisure Walking Based on the Demand of Behavior

Sustainability ◽

10.3390/su13084105 ◽

2021 ◽

Vol 13 (8) ◽

pp. 4105

Author(s):

Yupei Jiang ◽

Honghu Sun

Keyword(s):

Health Benefits ◽

Health Benefit ◽

Public Health Research ◽

Space Time ◽

Time Behavior ◽

Walking Behavior ◽

Face To Face ◽

Residential Neighborhood ◽

The Impact

Leisure walking has been an important topic in space-time behavior and public health research. However, prior studies pay little attention to the integration and the characterization of diverse and multilevel demands of leisure walking. This study constructs a theoretical framework of leisure walking behavior demands from three different dimensions and levels of activity participation, space-time opportunity, and health benefit. On this basis, through a face-to-face survey in Nanjing, China (N = 1168, 2017–2018 data), this study quantitatively analyzes the characteristics of leisure walking demands, as well as the impact of the built environment and individual factors on it. The results show that residents have a high demand for participation and health benefits of leisure walking. The residential neighborhood provides more space opportunities for leisure walking, but there is a certain constraint on the choice of walking time. Residential neighborhood with medium or large parks is more likely to satisfy residents’ demands for engaging in leisure walking and obtaining high health benefits, while neighborhood with a high density of walking paths tends to limit the satisfaction of demands for space opportunity and health benefit. For residents aged 36 and above, married, or retired, their diverse demands for leisure walking are more likely to be fulfilled, while those with high education, medium-high individual income, general and above health status, or children (<18 years) are less likely to be fulfilled. These finding that can have important implications for the healthy neighborhood by fully considering diverse and multilevel demands of leisure walking behavior.

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Size-resolved characterization of organic aerosol in the North China Plain: new insights from high resolution spectral analysis

Environmental Science: Atmospheres ◽

10.1039/d1ea00025j ◽

2021 ◽

Author(s):

Weiqi Xu ◽

Chun Chen ◽

Yanmei Qiu ◽

Conghui Xie ◽

Yunle Chen ◽

...

Keyword(s):

Radiative Forcing ◽

North China Plain ◽

North China ◽

Fine Particles ◽

Large Fraction ◽

Organic Aerosol ◽

Size Distributions ◽

The North ◽

The Impact

Organic aerosol (OA), a large fraction of fine particles, has a large impact on climate radiative forcing and human health, and the impact depends strongly on size distributions. Here we...

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Charged current Drell-Yan production at N3LO

Journal of High Energy Physics ◽

10.1007/jhep11(2020)143 ◽

2020 ◽

Vol 2020 (11) ◽

Cited By ~ 1

Author(s):

Claude Duhr ◽

Falko Dulat ◽

Bernhard Mistlberger

Keyword(s):

Cross Section ◽

Cross Sections ◽

Production Cross Section ◽

Production Cross ◽

Hadron Collider ◽

Charge Asymmetry ◽

Charged Current ◽

Leading Order ◽

Neutrino Pair ◽

The Impact

Abstract We present the production cross section for a lepton-neutrino pair at the Large Hadron Collider computed at next-to-next-to-next-to-leading order (N3LO) in QCD perturbation theory. We compute the partonic coefficient functions of a virtual W± boson at this order. We then use these analytic functions to study the progression of the perturbative series in different observables. In particular, we investigate the impact of the newly obtained corrections on the inclusive production cross section of W± bosons, as well as on the ratios of the production cross sections for W+, W− and/or a virtual photon. Finally, we present N3LO predictions for the charge asymmetry at the LHC.

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