Dip in muons and neutrons on 20 January

[andrew....@googlemail.com]

I know many people don't like ChatGPT but for what it is worth here is it's answer on why the dip on 20^th January probably occurred…….

 

My muon detector, and a number of other people's around the world, has shown significant dip in muon detector on 20 January 2026. A CME hit the atmosphere of Earth on 19 January 2026. Are the two related?

 

Yes — they’re very likely related. Here’s why:

📡 What happened on 19–20 January 2026

• A full-halo coronal mass ejection (CME) associated with an X1.9 solar flare on 18 January 2026 hit Earth on 19 January. This triggered a severe (G4) geomagnetic storm and elevated radiation conditions that persisted into 20 January.

🌍 How CMEs affect cosmic rays and muon detectors

Cosmic rays reaching Earth are mostly high-energy galactic particles. When intense solar activity drives large CMEs and associated magnetic disturbances into interplanetary space, those structures modify the local magnetic field environment through which galactic cosmic rays travel. Two key effects occur:

1. Forbush decreases — A transient drop in observed cosmic ray (and hence muon) flux when a CME’s magnetic field and shock front sweep past Earth and shield or scatter incoming galactic cosmic rays. These decreases are widely observed in neutron monitor, muon telescope, and similar detector networks.
2. Ground Level Enhancements (GLEs) — Sometimes an increase in counts due to high-energy solar particles, but such enhancements depend on the energy and directionality of the solar event. GLEs were not reported for this event, and instead the dominant signature was the decrease.

🧪 Why your muon detector dip matches

The timing of the dip (20 January) aligns well with the CME’s arrival and geomagnetic disturbance. During the passage of the CME’s magnetic cloud and shock structure, the effective galactic cosmic ray flux at Earth’s atmosphere was temporarily reduced — this is exactly the Forbush decrease phenomenon seen in global cosmic-ray networks, including both neutron and muon channels.

In other words:

• The CME disturbed the heliospheric magnetic field.
• This disturbance acted as a barrier/modulator to galactic cosmic rays.
• Muon detectors (sensitive to secondary cosmic rays produced in the atmosphere) registered a significant dip as a consequence.

So, yes — the observed muon rate drop on 20 January is consistent with the effects established by space weather science for strong CMEs and geomagnetic storms.

 

[flavio camacho]

Thanks so much.

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[Stephen Arbogast]

I like  ChatGPT    but   I  don't  trust it  entirely...   it gets me started on the  road.  

For  example    I am  working  with a GNU Radio   flow   graph   which  I am adapting  from   Marcus  Leech and  Pierre  Terrier   to  use  for  data collection  for  evaluation  by  ezCon.py   I did consult ChatGPT  for  advice    which  was very  generic and  of no use.

I  finally  figured out  my problem.  A gui check box in  a  gnu  radio  flow  graph is not a variable.  I  created  a  variable  in my  flow   graph  and assigned that  variable to  the  value  of my  gui  check box.  Then using that  variable in the  embedded python block  ezRAVectorLogger  I am now able to write out a  file useful to  ezRACon.py   I'm  getting  closer  but  needs more testing.   Here  is a  sample  of the  file ezRAVectorLogger output file....

Still  needs more testing...

[Andrew Thornett]

There is definitely a steep learning curve for GNU Radio, but I think it's worth it!

Andy

Sent from Outlook for Android

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From: 'Stephen Arbogast' via Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Sent: Sunday, February 1, 2026 12:31:20 AM
To: Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Subject: [SARA] Re: Dip in muons and neutrons on 20 January

 

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[Dimitry UA3AVR]

Andy, thanks for interesting observation and explanation. I wasn't familiar before with the Forbush mechanism ant thought that only increases are possible due to Coronal Mass Ejections.

ChatGPT makes mistakes, sometimes childish like incorrectly calculated coefficients in practical formulas. In the paid version too. Clarifying questions are needed every time after, and usually ChatGPT doesn't persist in mistakes. It is useful in extracting data from papers, their processing, numerical procedures, astronomy calculations etc.

If you need a review is some topic, help him by a list of references in journals with open access to papers. In the astronomy it is not a problem.

воскресенье, 1 февраля 2026 г. в 03:31:20 UTC+3, Stephen Arbogast: