Christian Grefe
@cgrefe.bsky.social
Particle physicist at University of Bonn, working on the ATLAS experiment at CERN. https://orcid.org/0000-0001-7050-5301
Pinned
Christian Grefe
@cgrefe.bsky.social
· Nov 12
I guess it is time for a re- #introduction: I am a researcher at the University of Bonn and work on the @atlasexperiment.bsky.social at CERN. I post mostly about particle #physics, academia in Germany ( #IchBinHanna), and life in Geneva. 🧪⚛️
Reposted by Christian Grefe
![Comic. Panels up to the 10-year point are grayed out. New panels since the Ten Years comic, which chronicles the first ten years of PERSON 1's journey with cancer: (1) [two people in bed] PERSON 1 (woman): One more chapter? PERSON 2 (man): Don’t we both have to get up early? PERSON 1: Nnnnnggggh PERSON 2: Sure, good point. (2) [many people wearing masks, walking while looking at graphs on their phones] (3) [birds landing on people] PERSON 2 in beanie and scarf: Hah! They like *my* seeds best. PERSON 1 in scarf holding phone with a bird sitting on it: Wait, how do I take a picture of this one? (4) [two people rowing boats with tree landscape] (5) [Person 1 carries overflowing stack of things to Person 2 in bed] PERSON 1: I brought you honey lemon tea, more pillows, a cinnamon roll, Tylenol, another blanket, a– PERSON 2: It was just Appendicitis, I’m really– PERSON 1: *It is my turn to take care of you and I am going to do it right!* (6) [Two people in car] (7) [still in car) PERSON 1: Oh my god. PERSON 2: Oh my god. (8) [car driving] PERSON 1: Pull over! PERSON 2: I am! (9) [both people get out of car] (10) [Large colored panel of aurora borealis over water with both people looking on] (11) [Person 1 sits against tree while Person 2 lies on the ground] PERSON 1: Fifteen years. No sign of the cancer. (12) I *am* having some weird symptoms. Joint pain. Fatigue. I think I’m losing my close-up vision. PERSON 2: Yeah. Me too. (13) PERSON 2: I think we’re getting old. (14) PERSON 1: I guess that’s okay. PERSON 2: It’s all I wanted.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:cz73r7iyiqn26upot4jtjdhk/bafkreihwhjblp5lyiwp63ouar7ocfea7evmckytoeo7rkfuoo4gw5rnrra@jpeg)
November 26, 2025 at 10:32 PM
Reposted by Christian Grefe
Liebe "PiA - Physik im Advent" FreundInnen, nur noch 10 Tage bis zum
Start von "PiA - Physik im Advent". JETZT anmelden:
www.physik-im-advent.de Bitte informiert auch Eure FreundInnen,
Lehrkäfte, Nachbarn ... #Physik #MINT #Bildung
#DigitaleBildung #Adventskalender #Advent #Schule #Lehrer
Start von "PiA - Physik im Advent". JETZT anmelden:
www.physik-im-advent.de Bitte informiert auch Eure FreundInnen,
Lehrkäfte, Nachbarn ... #Physik #MINT #Bildung
#DigitaleBildung #Adventskalender #Advent #Schule #Lehrer
November 21, 2025 at 4:10 PM
Liebe "PiA - Physik im Advent" FreundInnen, nur noch 10 Tage bis zum
Start von "PiA - Physik im Advent". JETZT anmelden:
www.physik-im-advent.de Bitte informiert auch Eure FreundInnen,
Lehrkäfte, Nachbarn ... #Physik #MINT #Bildung
#DigitaleBildung #Adventskalender #Advent #Schule #Lehrer
Start von "PiA - Physik im Advent". JETZT anmelden:
www.physik-im-advent.de Bitte informiert auch Eure FreundInnen,
Lehrkäfte, Nachbarn ... #Physik #MINT #Bildung
#DigitaleBildung #Adventskalender #Advent #Schule #Lehrer
Reposted by Christian Grefe
Happy #PrideinSTEMDay! 🏳️🌈🏳️⚧️
ATLAS proudly celebrates the incredible diversity of our scientific community. Our varied backgrounds, perspectives and identities drive excellence in research. We are committed to advancing the recognition and representation of our LGBTQ+ colleagues — today and every day.
ATLAS proudly celebrates the incredible diversity of our scientific community. Our varied backgrounds, perspectives and identities drive excellence in research. We are committed to advancing the recognition and representation of our LGBTQ+ colleagues — today and every day.
November 18, 2025 at 3:08 PM
Happy #PrideinSTEMDay! 🏳️🌈🏳️⚧️
ATLAS proudly celebrates the incredible diversity of our scientific community. Our varied backgrounds, perspectives and identities drive excellence in research. We are committed to advancing the recognition and representation of our LGBTQ+ colleagues — today and every day.
ATLAS proudly celebrates the incredible diversity of our scientific community. Our varied backgrounds, perspectives and identities drive excellence in research. We are committed to advancing the recognition and representation of our LGBTQ+ colleagues — today and every day.
Reposted by Christian Grefe
Es geht wieder los mit der Reform des #WissZeitVG! Der letzte Versuch ist geplatzt, weil die 🚦 auseinandergeflogen ist. Aber: Seitdem liegen aussichtsreiche Lösungen für das Kernproblem Postdoc-Phase auf dem Tisch! Wie lassen sich Befristungen in dieser Phase eindämmen? 5 Instrumente: ⬇️ #IchBinHanna
Wird Zeit fürs WissZeitVG: Auf ein Neues!
Die Reform-Debatte nimmt wieder an Fahrt auf -- Grund genug, uns aussichtsreiche Lösungen für die Kernproblematik der Postdoc-Phase ins Gedächtnis zu rufen!
steady.page
November 18, 2025 at 8:11 AM
Es geht wieder los mit der Reform des #WissZeitVG! Der letzte Versuch ist geplatzt, weil die 🚦 auseinandergeflogen ist. Aber: Seitdem liegen aussichtsreiche Lösungen für das Kernproblem Postdoc-Phase auf dem Tisch! Wie lassen sich Befristungen in dieser Phase eindämmen? 5 Instrumente: ⬇️ #IchBinHanna
Reposted by Christian Grefe
Heavy-ion season is here! 💥
The ATLAS Experiment at @cern.bsky.social has recorded its first lead-lead collisions of 2025, marking the start of three weeks of heavy-ion running at 5.36 TeV per nucleon pair. Take a look at some of our first spectacular event displays!
The ATLAS Experiment at @cern.bsky.social has recorded its first lead-lead collisions of 2025, marking the start of three weeks of heavy-ion running at 5.36 TeV per nucleon pair. Take a look at some of our first spectacular event displays!
November 18, 2025 at 9:55 AM
Heavy-ion season is here! 💥
The ATLAS Experiment at @cern.bsky.social has recorded its first lead-lead collisions of 2025, marking the start of three weeks of heavy-ion running at 5.36 TeV per nucleon pair. Take a look at some of our first spectacular event displays!
The ATLAS Experiment at @cern.bsky.social has recorded its first lead-lead collisions of 2025, marking the start of three weeks of heavy-ion running at 5.36 TeV per nucleon pair. Take a look at some of our first spectacular event displays!
Reposted by Christian Grefe
Es geht wieder los mit der Reform des #WissZeitVG! Diesmal muss es was werden, faire Bedingungen überfällig: Was ich 2023 gesagt habe, gilt weiterhin! ⬇️ @drkeichhorn.bsky.social, @kubon.bsky.social & ich haben uns in der letzten Runde intensiv für #IchBinHanna eingesetzt, werden’s auch diesmal tun.💪
November 17, 2025 at 6:04 PM
Es geht wieder los mit der Reform des #WissZeitVG! Diesmal muss es was werden, faire Bedingungen überfällig: Was ich 2023 gesagt habe, gilt weiterhin! ⬇️ @drkeichhorn.bsky.social, @kubon.bsky.social & ich haben uns in der letzten Runde intensiv für #IchBinHanna eingesetzt, werden’s auch diesmal tun.💪
Reposted by Christian Grefe
![Comic. [Person with ponytail pointing at diagram while speaking to three other people] PERSON: If the emergency stop is activated, any riders on the waterslide will be diverted into the beam dump, a large graphite block which will safely absorb their momentum. [caption] We regretted hiring an accelerator physicist to design our water park.](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:cz73r7iyiqn26upot4jtjdhk/bafkreicnzdnpjdz4clfa2uhx6isbdwgu72oku5pee4av7paavbjmqpyoiu@jpeg)
November 18, 2025 at 3:40 AM
Reposted by Christian Grefe
Students, apply for a CERN summer studentship. Greatest experience ever!
Deadline 26 January 2026. careers.cern/programmes/s...
(It's not just for physicists. Check it out.)
Deadline 26 January 2026. careers.cern/programmes/s...
(It's not just for physicists. Check it out.)
Summer Studentship
Programme overview Join the CERN Summer Student Programme and dive into cutting-edge research. You’ll work on advanced scientific and technical projects, contributing directly to CERN’s…
careers.cern
November 15, 2025 at 3:24 PM
Students, apply for a CERN summer studentship. Greatest experience ever!
Deadline 26 January 2026. careers.cern/programmes/s...
(It's not just for physicists. Check it out.)
Deadline 26 January 2026. careers.cern/programmes/s...
(It's not just for physicists. Check it out.)
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.
November 14, 2025 at 2:59 PM
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.
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.
November 13, 2025 at 10:00 PM
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.
Zählt so ein Social-Media Gig zu den Höchstbefristungszeiten nach WissZeitVG? #IchBinHanna
November 13, 2025 at 9:57 AM
Zählt so ein Social-Media Gig zu den Höchstbefristungszeiten nach WissZeitVG? #IchBinHanna
Die aktuelle Ausgabe des Physik Journal der DPG illustriert einen Artikel mit einem offensichtlich KI-generierten Bild - natürlich ohne Quellenangabe oder sonst irgendeinem Hinweis. Peinlich und vollkommen überflüssig.
November 11, 2025 at 2:35 PM
Die aktuelle Ausgabe des Physik Journal der DPG illustriert einen Artikel mit einem offensichtlich KI-generierten Bild - natürlich ohne Quellenangabe oder sonst irgendeinem Hinweis. Peinlich und vollkommen überflüssig.
Vor 10 Jahren habe ich am CERN eine Schülerpraktikantin im Rahmen des Netzwerks Teilchenwelt betreut. Vorhin kam die Ankündigung für ihr Promotionskolloquium in meinem Postfach an 😊
November 11, 2025 at 7:54 AM
Vor 10 Jahren habe ich am CERN eine Schülerpraktikantin im Rahmen des Netzwerks Teilchenwelt betreut. Vorhin kam die Ankündigung für ihr Promotionskolloquium in meinem Postfach an 😊
Reposted by Christian Grefe
🎤 Are you passionate about science? Show us! 😉
To mark the 20th anniversary of FameLab International, CERN is teaming up with FameLab to invite you to share your love for science and win fantastic prizes.
To mark the 20th anniversary of FameLab International, CERN is teaming up with FameLab to invite you to share your love for science and win fantastic prizes.
November 3, 2025 at 8:24 AM
🎤 Are you passionate about science? Show us! 😉
To mark the 20th anniversary of FameLab International, CERN is teaming up with FameLab to invite you to share your love for science and win fantastic prizes.
To mark the 20th anniversary of FameLab International, CERN is teaming up with FameLab to invite you to share your love for science and win fantastic prizes.
Reposted by Christian Grefe
"Es war nicht eine kleine Zahl von Verbrechern, es waren Hunderttausende einer sogenannten deutschen Elite, Männer, Jungen & entmenschte Weiber, die unter dem Einfluss verrückter Lehren in kranker Lust diese Taten begangen haben."
Thomas Mann
9. November 1938
Thomas Mann
9. November 1938
November 9, 2025 at 7:25 AM
"Es war nicht eine kleine Zahl von Verbrechern, es waren Hunderttausende einer sogenannten deutschen Elite, Männer, Jungen & entmenschte Weiber, die unter dem Einfluss verrückter Lehren in kranker Lust diese Taten begangen haben."
Thomas Mann
9. November 1938
Thomas Mann
9. November 1938
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.
November 7, 2025 at 7:40 AM
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.
Alle die ein wirklich sicheres Passwort brauchen sollten diesen Empfehlungen folgen: neal.fun/password-game/
November 6, 2025 at 1:46 PM
Alle die ein wirklich sicheres Passwort brauchen sollten diesen Empfehlungen folgen: neal.fun/password-game/
Reposted by Christian Grefe
In honor of the upcoming #WomenInPhysics Day, let's create a thread of amazing women physicists. I'll start with one my favorites, Chien-Shiung Wu, who is best known for conducting the Wu experiment, which proved that parity is not conserved. ⚛️ 🧪 👩🔬 🎢
November 4, 2025 at 10:54 PM
In honor of the upcoming #WomenInPhysics Day, let's create a thread of amazing women physicists. I'll start with one my favorites, Chien-Shiung Wu, who is best known for conducting the Wu experiment, which proved that parity is not conserved. ⚛️ 🧪 👩🔬 🎢
Reposted by Christian Grefe
POV: Preparing to investigate the mysteries of #DarkMatter 🌌
In honour of #DarkMatterDay, we accompanied Baptiste, an @atlasexperiment.bsky.social physicist studying dark matter, as he gears up for his day of detective work.
In honour of #DarkMatterDay, we accompanied Baptiste, an @atlasexperiment.bsky.social physicist studying dark matter, as he gears up for his day of detective work.
October 31, 2025 at 10:59 AM
POV: Preparing to investigate the mysteries of #DarkMatter 🌌
In honour of #DarkMatterDay, we accompanied Baptiste, an @atlasexperiment.bsky.social physicist studying dark matter, as he gears up for his day of detective work.
In honour of #DarkMatterDay, we accompanied Baptiste, an @atlasexperiment.bsky.social physicist studying dark matter, as he gears up for his day of detective work.
Reposted by Christian Grefe
Let's go on a Dark Matter Hunt!
It's almost Dark Matter Day -- also known as Halloween 👻 🎃 -- and I'm really excited to be heading to the STFC’s Boulby Underground Laboratory! This is a unique facility where scientists hunt for the missing matter that makes up our Universe. 🌌
It's almost Dark Matter Day -- also known as Halloween 👻 🎃 -- and I'm really excited to be heading to the STFC’s Boulby Underground Laboratory! This is a unique facility where scientists hunt for the missing matter that makes up our Universe. 🌌
October 29, 2025 at 11:41 PM
Let's go on a Dark Matter Hunt!
It's almost Dark Matter Day -- also known as Halloween 👻 🎃 -- and I'm really excited to be heading to the STFC’s Boulby Underground Laboratory! This is a unique facility where scientists hunt for the missing matter that makes up our Universe. 🌌
It's almost Dark Matter Day -- also known as Halloween 👻 🎃 -- and I'm really excited to be heading to the STFC’s Boulby Underground Laboratory! This is a unique facility where scientists hunt for the missing matter that makes up our Universe. 🌌
Reposted by Christian Grefe
Here’s a gift link to the piece I wrote for @zeit.de:
A history of the Republican Party and a rightwing radicalization, unfolding over decades, that ultimately paved the way for Trump’s rise.
www.zeit.de/kultur/2025-...
A history of the Republican Party and a rightwing radicalization, unfolding over decades, that ultimately paved the way for Trump’s rise.
www.zeit.de/kultur/2025-...
US-Republikaner: Wie sich die Republikaner selbst vernichtet haben
Extremismus und Geschwurbel gehören heute zum Kern der US-Republikaner. In fünf Etappen hat sich die Partei radikalisiert. Und nein, es begann nicht erst 2016 mit Trump.
www.zeit.de
October 29, 2025 at 1:18 PM
Here’s a gift link to the piece I wrote for @zeit.de:
A history of the Republican Party and a rightwing radicalization, unfolding over decades, that ultimately paved the way for Trump’s rise.
www.zeit.de/kultur/2025-...
A history of the Republican Party and a rightwing radicalization, unfolding over decades, that ultimately paved the way for Trump’s rise.
www.zeit.de/kultur/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.
October 28, 2025 at 2:54 PM
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.
Applying weights of 100% (last), 90% (1st), 50% (2nd) and 10% for anybody else in larger collaborations is wild, especially if the convention is to publish in alphabetical order 🤨
🧪For those of us who do complex collaborations with multiple corresponding authors this is terrible . I suspect it will also hit female authors disproportionately as they tend to have more collaborations across fields…https://www.nature.com/articles/d41586-025-03281-4
Google Scholar tool gives extra credit to first and last authors
Researchers welcome the initiative, but say it doesn’t go far enough to capture the nuance of researcher productivity and impact.
www.nature.com
October 27, 2025 at 5:30 AM
Applying weights of 100% (last), 90% (1st), 50% (2nd) and 10% for anybody else in larger collaborations is wild, especially if the convention is to publish in alphabetical order 🤨
No large particle collider in China in the near future. "CEPC will not be considered for inclusion in China’s next five-year plan (2026–2030)" ⚛️🧪 cerncourier.com/a/cepc-matur...
CEPC matures, but approval is on hold – CERN Courier
The Circular Electron–Positron Collider (CEPC), a 100-km electron–positron “Higgs factory” proposed in China, has reached the technical-design stage but will not be included for approval or constructi...
cerncourier.com
October 26, 2025 at 4:58 PM
No large particle collider in China in the near future. "CEPC will not be considered for inclusion in China’s next five-year plan (2026–2030)" ⚛️🧪 cerncourier.com/a/cepc-matur...
50000000000000000 proton-proton collisions is a lot of data to analyse. Thanks a lot LHC! To put this in perspective, that should correspond to roughly 30000000 produced Higgs bosons.
Gearing up for higher-luminosity 💫
Yesterday, the Large Hadron Collider hit a new record – 500 inverse femtobarns (fb-1), equivalent to 50 million billion collisions, delivered to the @atlasexperiment.bsky.social and @cmsexperiment.bsky.social since it began operations in 2010.
Yesterday, the Large Hadron Collider hit a new record – 500 inverse femtobarns (fb-1), equivalent to 50 million billion collisions, delivered to the @atlasexperiment.bsky.social and @cmsexperiment.bsky.social since it began operations in 2010.
October 23, 2025 at 2:21 PM
50000000000000000 proton-proton collisions is a lot of data to analyse. Thanks a lot LHC! To put this in perspective, that should correspond to roughly 30000000 produced Higgs bosons.