iiinova — where your digital self keeps evolving

Christian Grefe @cgrefe.bsky.social · 29/09/2026

Unser Institut ist bunter geworden www.instagram.com/reel/Dd33VvS...

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Christian Grefe @cgrefe.bsky.social · 29/09/2026

Einfach die Google KI fragen 🫠

Vorschlag von Google translate: "Chickened out - ausgeflippt"

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Christian Grefe @cgrefe.bsky.social · 15/09/2026

All day meetings back-to-back so I decided I deserve an ice cream break in the botanical garden.

Das Poppelsdorfer Schloss im botanischen Garten der Uni Bonn.

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Christian Grefe @cgrefe.bsky.social · 10/09/2026

Is anybody else getting coffee mugs for their published papers?

Coffee mug showing the title and a figure from https://link.springer.com/article/10.1007/JHEP03(2025)010

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Christian Grefe @cgrefe.bsky.social · 01/09/2026

Aus den Nutzungsbedingungen der gemeinsamen LLM-Lösung der Hochschulen in NRW 🫠

"Die Nutzung des Dienstes hat ausschließlich zu Zwecken von Studium, Lehre, Forschung, Qualifikationsverfahren wie Promotion und Habilitation, Hochschulverwaltung und für Aufgaben, für die die Hochschule die Verantwortliche ist, stattzufinden."

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Christian Grefe @cgrefe.bsky.social · 12/08/2026

We had great views for the maximum and the homemade pinhole camera worked perfectly.

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Christian Grefe @cgrefe.bsky.social · 12/08/2026

Perfect cloud for watching the eclipse in Geneva.

View over lake Geneva from Eaux-Vives plage towards the Jura. The sun is behind a cloud.

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Christian Grefe @cgrefe.bsky.social · 12/07/2026

Müssen grüne Männer überhaupt pumpen?

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Christian Grefe @cgrefe.bsky.social · 02/07/2026

A new challenging task has appeared on my desk. atlas.cern/Resources/Co...

Picture of the new ATLAS experiment colouring book.

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Christian Grefe @cgrefe.bsky.social · 13/06/2026

Geneva is bracing for the G7 protests. Basically all shop windows in downtown Geneva are barricaded. Police patrols everywhere and helicopters flying all day.

A group of policemen in front of a Tiffany & Co with barricaded windows.

Versace boutique with barricaded windows.

Barricaded windows with graffiti. One shows the eagle of the Geneva flag, the other shows a tram at Bel-Air next to the Rhône.

Three barricaded windows with graffiti. One shows the jet d'eau, the other two show a text "La paix est un ..."

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Christian Grefe @cgrefe.bsky.social · 03/06/2026

Replying to an e-mail the next day, quickly followed by "Thanks for the quick reply".

A picture of Fry from Futurama squinting, overlaid with text: "Not sure if sarcasm or serious"

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Christian Grefe @cgrefe.bsky.social · 28/05/2026

Thanks to God. I was really desperate where to put all my money.

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Christian Grefe @cgrefe.bsky.social · 27/05/2026

Heute hatten wir eine Delegation des Forschungsausschusses des Deutschen Bundestages zu Gast. Die Abgeordneten durften u.A. den ATLAS Kontrollraum besuchen. Zeit war wie immer bei solchen Besuchen sehr knapp, aber hoffentlich haben sie Abgeordneten mitgenommen wie wichtig die deutschen Beiträge sind

Mitglieder des Deutschen Bundestages besuchen den ATLAS Kontrollraum.

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Christian Grefe @cgrefe.bsky.social · 13/05/2026

We also manage to keep a very good reconstruction efficiency for the primary interaction vertex, even in events with more than 60 simultaneous proton-proton collisions. The ATLAS detector was originally designed to handle 20 simultaneous proton-proton collisions.

Number of reconstructed primary vertices as a function of the number of simulated pp interactions per bunch crossing in simulated tt events.

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Christian Grefe @cgrefe.bsky.social · 13/05/2026

We achieve more than 90% reconstruction efficiency in even the most challenging topologies like events with two top quarks, and a relative precision on 1/pT of better than 5%.

Relative q/pT resolution for track seeds, track candidates, and selected tracks as a function of the η of the generator-level particles to which they are matched. The resolutions represent the average over the full pT spectrum of the sample. The observed asymmetries in the distributions for seeds are due to the inactive modules included in the simulation, to reflect data taking conditions during Run 2.

Efficiency to reconstruct a track seed, a track candidate and a final silicon track as a function of the true particle η.

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Christian Grefe @cgrefe.bsky.social · 13/05/2026

The challenge is to precisely reconstruct the trajectories of up to several thousands of particles from the ionisation signals they create within the different detector parts. The event below is from a special test with around 150 simultaneous collisions. The usual data we record "only" has about 60

A visualization of an event recorded by the ATLAS experiment (run 508073, event 22881991) on October 8, 2025, when the Large Hadron Collider accelerator was providing proton-proton collisions at 13.6 TeV with a "high-mu" setup.

In a "high-mu" setup, the proton beams in the accelerator are focused and directed to produce a high number of collisions per bunch crossing. The event visualized here was recorded in a collision with an average of 150 proton-proton interactions, and 92 primary vertices were reconstructed.

The image shows three views of the same event. The top left view shows a transversal view of the event, where, from the center, the tracks of the charged particles as reconstructed in the inner detectors are displayed (multicolor lines) as well as the energy deposits (yellow bars) in the electromagnetic and hadronic calorimeters. A blue line shows the reconstructed track of a muon. The bottom view shows the same event in a longitudinal projection, where the reconstructed 92 primary vertices are also shown, visualized as white spheres. The right view shows the energy deposits in the calorimeters represented on a projected surface of the ATLAS detector; this kind of plot (called a "Lego plot") shows the overall activity of an event.

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Christian Grefe @cgrefe.bsky.social · 13/05/2026

New #paper is out: a comprehensive description of the pattern recognition algorithms we are using to reconstruct charged particle tracks in the @atlasexperiment.bsky.social Inner Detector. 🧪⚛️

Illustration of the stages of inside-out track pattern recognition in a simplified representation of the Inner Detector transverse plane. The silicon space points are shown in yellow, and TRT drift circles in orange. The seeds reconstructed from combinations of space points are indicated in blue. The dashed blue seed illustrates a case where two seeds correspond to the trajectory of the same charged particle. The green seed is rejected by the requirement that the seed be consistent with a particle from the nominal interaction point. The track candidates are shown with lines. The green dashed track candidate is rejected because it is inconsistent with the nominal interaction point. The black track candidate is reconstructed up to the CKF stage. The red track candidates are fully reconstructed silicon tracks fit with the global χ2 where an extension into the TRT is possible.

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Christian Grefe @cgrefe.bsky.social · 13/05/2026

Seit der Entscheidung zur Anpassung der Regelaltersgrenze der gesetzlichen RV von 2007 ist das Rentenalter stärker angestiegen als die Lebenserwartung. Ich würde von Journalisten erwarten, dass sie solche faktenfreien Aussagen wie diese von Herrn Nagel besser einordnen und nicht nur wiedergeben.

Entwicklung der Lebenserwartung in Ost- und Westdeutschland seit der Wiedervereinigung. Quelle: https://www.destatis.de/DE/Themen/Gesellschaft-Umwelt/Bevoelkerung/Sterbefaelle-Lebenserwartung/sterbetafel.html

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Christian Grefe @cgrefe.bsky.social · 27/04/2026

Um 1900 sah der Platz so aus. Die Gärten wurden in den 1930er Jahren von den Nazis entfernt um den Platz als Aufmarschplatz zu nutzen. Quelle: www.gendarmenmarkt.de/geschichte-d...

Historische Ansicht des Gendarmenmarktes um 1900. Blick auf das Konzerthaus und den Französischen Dom. Im Vordergrund sind Gärten zu sehen. Quelle: https://www.gendarmenmarkt.de/geschichte-des-gendarmenmarktes-berlin-mitte.htm

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Christian Grefe @cgrefe.bsky.social · 14/04/2026

Hilarious job advertisement by CERN. A fixed term limited duration job in the FCC group is advertised as "Lead Experimental Particle Physicist", while the single annual permanent position with open profile, among the most prestigious positions in the field, is advertised as "Experimental Physicist"

Screenshot of the CERN job advertisement page

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Christian Grefe @cgrefe.bsky.social · 31/03/2026

LHCb collecting more integrated luminosity than ATLAS and CMS. I don't remember seeing this ever.

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Christian Grefe @cgrefe.bsky.social · 18/03/2026

I just finished chairing a session on the measurement of double Higgs boson production with 8 fantastic talks by PhD and master students from ATLAS, CMS and theory. I did not even get to use my -1 minute sign 😢

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Christian Grefe @cgrefe.bsky.social · 18/03/2026

Diese Woche bei der Frühjahrstagung der @dpgphysik.bsky.social in Erlangen und so langsam spielt auch das Wetter mit.

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Christian Grefe @cgrefe.bsky.social · 18/03/2026

Die Pizza hat möglicherweise geholfen die Veranstaltung noch etwas attraktiver zu machen 😉

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Christian Grefe @cgrefe.bsky.social · 18/03/2026

Vor 10 Jahren haben wir mit einer handvoll Leuten yhep.desy.de gegründet. Heute war der Hörsaal voll gepackt mit mehr als 100 early-career Physiker*innen die über das #WissZeitVG und Nachhaltigkeit in der Wissenschaft informiert wurden und sich vernetzen konnten. #IchBinHanna

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Christian Grefe @cgrefe.bsky.social · 04/03/2026

Unfortunately the particle physics disappeared from the 200CHF bill

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Christian Grefe @cgrefe.bsky.social · 13/02/2026

Relative Veränderung der Erwerbstätigkeit nach der Geburt des ersten Kindes. In Deutschland ist der Unterschied zwischen Männern und Frauen besonders groß. Wer weniger Arbeitnehmer in Teilzeit möchte muss die Betreueungsangebote verbessern.

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Christian Grefe @cgrefe.bsky.social · 09/02/2026

Particle physicists are somewhere in between astrophysicists and travel bloggers 😂

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Christian Grefe @cgrefe.bsky.social · 06/02/2026

Four months after inheriting this office orchid it decided to flower again.

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Christian Grefe @cgrefe.bsky.social · 26/12/2025

Ausnahmsweise keine Berge die den Horizont versperren

Silhouette von Bäumen im Licht der Dämmerung

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Christian Grefe @cgrefe.bsky.social · 12/12/2025

Outreach, diversity and career aspects are now also mentioned explicitly in the recommendations.

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Christian Grefe @cgrefe.bsky.social · 12/12/2025

Sustainability is now more prominently mentioned with a dedicated section (was grouped with impact on society in the last iteration from 2020)

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Christian Grefe @cgrefe.bsky.social · 12/12/2025

The major new decision is the decision for the FCCee as the next major flagship collider to be realised at CERN in the 2040s after the conclusion of the HL-LHC programme.

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Christian Grefe @cgrefe.bsky.social · 12/12/2025

As already in previous updates, the realisation and success of the High Luminosity upgrade of the LHC has highest priority. The project is fully funded and the upgrades will be installed between 2026 and 2030.

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Christian Grefe @cgrefe.bsky.social · 08/12/2025

Just checked and all is still good here as well. I also started thinking about data science applications for our membership database...

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Christian Grefe @cgrefe.bsky.social · 03/12/2025

Speaking of low standards. Die Empfehlung des Schweizer Bundesamtes für Gesundheit ist mindestens 2 alkoholfreie Tage pro Woche??? 🤯

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Christian Grefe @cgrefe.bsky.social · 14/11/2025

Last part of the 2025 LHC physics programme has just started. We will take 3 weeks of heavy ion collision data before going to a short end of year break in December.

LHC Page1 reporting first PbPb stable beam collisions in 2025

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Christian Grefe @cgrefe.bsky.social · 13/11/2025

Was fun to see so many friends and colleagues on the big screen 😃 Not sure when and where "the peace particle" movie will be screened for a wider audience, but I can definitely recommend it.

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Christian Grefe @cgrefe.bsky.social · 07/11/2025

Amateurs 😄 The @atlasexperiment.bsky.social has to detect particle collisions every 25ns (40MHz). Then our first level trigger system has about 2.5 microseconds to analyse and decide whether to keep each of these events and pass it to the second level trigger before the buffers overflow.

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Christian Grefe @cgrefe.bsky.social · 28/10/2025

Why on earth needs a scientific publisher like Elsevier a "Director of Generative AI"? Why do we need AI-supported peer review? I want to read about original research not some plausible-sounding made up garbage.

Publicity e-mail from Elsevier promoting their "AI-supported peer review".

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Christian Grefe @cgrefe.bsky.social · 23/10/2025

In der Hinsicht war ich letztes Jahr tatsächlich positiv überrascht von Stark Watzinger. Keine merkwürdigen Anmerkungen über eigenes (Un)wissen in Naturwissenschaften sondern tatsächlich relativ sinnvolle und interessierte Nachfragen.

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Christian Grefe @cgrefe.bsky.social · 05/10/2025

Da ist man zwei Wochen nicht in Genf in dann so etwas...

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Christian Grefe @cgrefe.bsky.social · 01/10/2025

Ähnlich übrigens in der Schweiz, das eigentlich nur zwei Hauptachsen hat, und darüber hinaus viel kürzere Strecken hat.

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Christian Grefe @cgrefe.bsky.social · 01/10/2025

Natürlich macht Japan einen besseren Job bei der Bahninfrastruktur, trotzdem kann man die Komplexität der beiden Schienennetze einfach nicht vergleichen. Die größten Verspätungen hat man in Deutschland wenn man einen Anschluss verpasst. Japan hat nur eine lange Linie mit ein paar Abzweigungen.

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