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@davidkelliher.bsky.social

Accelerator Physicist

69 Followers  |  96 Following  |  35 Posts  |  Joined: 11.11.2024  |  1.7186

Latest posts by davidkelliher.bsky.social on Bluesky

SVG Clock

A clock whos hands and dials cover vast timescales from seconds to epochs stephenbrooks.org/misc/clock.h...

17.09.2025 08:27 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
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Good to be back at @imperialcollegeldn.bsky.social for the FFA'25 workshop

16.09.2025 14:23 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
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Day 2 at the IOP PAB conference taking place in Oxford today

10.07.2025 08:52 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

#ipac25

02.06.2025 06:26 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
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Xeuying Lu explained how reducing the RF pulse duration, tau, helps get around the breakdown limit - empirically the limit scales with tau to the power of 5

02.06.2025 06:08 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0
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Proton and heavy ion beam power over time presented by Kanemura-san of FRIB #ipac25

02.06.2025 03:51 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
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SY Lee showed these nice experimental measurement of Lissajous curves #ipac25

02.06.2025 03:44 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Papers submitted! #ipac25

28.05.2025 15:20 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

For accelerator physicists everywhere it's IPAC submission deadline day! #ipac25

28.05.2025 07:17 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Nice explanation! I happen to use a CRT electron gun in a accelerator physics experiment.

Minor point - I think the steering was done with electrostatic fields not magnets

22.03.2025 14:32 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
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For accelerator physicists the black line depicts the microwave instability threshold in the complex normalised impedance plane in the case of a Gaussian momentum distribution. For plasma physicists - this is just another way of looking at the plasma dispersion function!

22.03.2025 12:49 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Nice to see some Lie operators!

11.03.2025 21:58 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0

This is much worse than the quoted exchange conveys. Particularly Trump's response to Mills, "we are the federal law." Just absolute tyranny shit.

21.02.2025 20:42 β€” πŸ‘ 153    πŸ” 36    πŸ’¬ 13    πŸ“Œ 2
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Black holes, particle physics and dark matter: What is CERN, and why is Ireland applying to join? Ireland is set to apply for associate membership status of the major European scientific body today – but why has it taken so long?

Ireland is set to apply for associate membership status of major European scientific body CERN today – but what is CERN, and why has it taken so long for us to join?
jrnl.ie/6626235

19.02.2025 08:27 β€” πŸ‘ 17    πŸ” 7    πŸ’¬ 0    πŸ“Œ 2

So it turns out the integers in the array were declared as 16-bit using the function SELECTED_INT_KIND whereas when split in two steps it was converted into 32-bit

05.02.2025 16:20 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Ah...I think you cracked it. It's failing at 2^8. Thanks!

04.02.2025 17:17 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 2    πŸ“Œ 0
Fortan output

Fortan output

This is an example of how it occurs in the wild. (p,i,j) are the array indices

04.02.2025 16:23 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0

The good old ZX Spectrum with its rubber keyboard!

04.02.2025 08:50 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
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USPAS | Programs | TBA University (2025) Homepage for the summer 2025 USPAS session sponsored by TBA University

Applications open for the summer 2025 session of the US Particle Accelerator School:
uspas.fnal.gov/programs/202...

03.02.2025 20:31 β€” πŸ‘ 7    πŸ” 5    πŸ’¬ 0    πŸ“Œ 0

Just came upon a strange gfortran bug. ABS() which should return the absolute value somehow returned a negative value. It occurred when operating on a single array element
ABS(arr(i,j)).
The fix is to split steps
M = arr(i,j) followed by
ABS(M)

Anyone come across this?

03.02.2025 14:08 β€” πŸ‘ 4    πŸ” 0    πŸ’¬ 2    πŸ“Œ 0
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This is another I found on my lunchtime walk

31.01.2025 17:22 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
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Harwell campus festures some eye-catching buildings at various stages of construction. This one looks fairly complete ...

31.01.2025 17:20 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0

His comments were unbelievably crass!

31.01.2025 17:15 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0
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The alternative approach- stack several cycles on the outer radius of a fixed field accelerator. This increases the intensity for low rep rate target

24.01.2025 14:12 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
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Beams circulating in a ring before extraction to one of target stations (in reality the split happens later along a common extraction line)

24.01.2025 14:05 β€” πŸ‘ 2    πŸ” 0    πŸ’¬ 1    πŸ“Œ 0
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Beam stacking experiment at a fixed field alternating gradient accelerator Beam stacking experiments in an FFA to reduce space charge effect.

Here's the link to the paper link.aps.org/doi/10.1103/...

20.01.2025 10:39 β€” πŸ‘ 0    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0
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Our beam stacking paper earned an Editor Suggestion accolade!

20.01.2025 09:13 β€” πŸ‘ 2    πŸ” 1    πŸ’¬ 1    πŸ“Œ 0
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Photo taken on Brighton beach yesterday by @fengho1.bsky.social

03.01.2025 20:51 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

Message to #GenX - check your blood pressure regularly!

I didn't and was diagnosed with hypertension a month ago after a few days of rapid heartbeat. Before that I was experiencing tinnitus which I failed to link to blood pressure.

I reckon lack of exercise over the course of a decade did for me.

31.12.2024 12:58 β€” πŸ‘ 1    πŸ” 0    πŸ’¬ 0    πŸ“Œ 0

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