Observing with Street Lights

Observing with Street Lights
Dark sky sites not always necessary to see the Milky Way (This image was taken ouside of a B&B in Julian, CA)

Sunday, April 25, 2021

How low is the July sun in the night sky in Iceland? What is the Muon g-2 experiment and findings?

 Greetings from Palmia Observatory

Well as we look forward to our upcoming cruise to Iceland, we are glad to find that the people there, with low rate of COVID-19, especially welcome US passengers and don't have many restrictions.  So, now we can return to possible astronomical sightings of the Northern Lights, while there?

Hmm, Iceland in July is going to have long days and short nights and it is not likely to have very dark skies at that time.  To check out the details, look at this SkySafariPro screenshot showing the path of the sun and how it just barely goes below the horizon and even at 1:00 AM, the sun is just a little bit more than 3 degrees below the horizon.  In fact the sky at 1:00 AM there will be about at dark as 7:40 PM here in OC.  Yep, going to be spending more time at the bar and less time with my DSLR and flimsy tripod pointed at the night sky!

SkySafariPro prediction for sun in night sky in July in Iceland (Source: Palmia Observatory)
SkySafariPro prediction for sun in night sky in July in Iceland (Source: Palmia Observatory)


Just to confirm how dark the sky would appear with the sun just 2-3 degrees below the horizon, this cell phone photo shows how bright the sky appears now in OC.  This brightness here in OC is considered to be about the same brightness that would be seen in Iceland with the sun in July just 2-3 degrees below the horizon at 1:00 AM.  Yep, we are going to spend more time enjoying the natural daytime beauty in Iceland in lieu of the night sky!

Eastward view of the sky at 7:40pm (Source: Palmia Observatory)
Eastward view of the sky at 7:40pm (Source: Palmia Observatory)



In other physicist wannabe news we can return to one of the session at the APS April meeting that discussed the latest experimental findings from the Fermilab's Muon g-2 experiment.  The announcement from Fermilab is shown below..

Fermilab announcement of the Muon g-2 experiment (Source: news.fnal.gov)
Fermilab announcement of the Muon g-2 experiment (Source: news.fnal.gov)

So this Fermilab experiment and results repeats an earlier experiment conducted at Brookhaven National Labs.  At that time, the statistical significance of the results was not impressive enough to generate a lot of concern, but it did cause a lot of folks to being to wonder what might be the case if it turned out to be true.  So Fermilab acquired the giant magnet used in that experiment and transported it back to Fermilab and assembled a large team of multidisciplinary experiments to repeat and improve the statistics of that original experiment.  Here David Hertzog explains the latest results at the APS April meeting.

Discussion of the Muon g-2 experiment and results (Source: D. Hertzog, APS April 2021)
Discussion of the Muon g-2 experiment and results (Source: D. Hertzog, APS April 2021)


Here we see the latest experimental results.  Not that we understand anything about what the experiment means, but at least we see they increased the statistical precision of the original experiment.

The Muon g-2  results from Run-1  (Source: D. Hertzog, APS April 2021)
The Muon g-2  results from Run-1  (Source: D. Hertzog, APS April 2021)


So, what was the fundamental physics principle under investigation?  It had to do with two measurements of the spin of a particle in a magnetic field.  The experiment compared the predicted results as computed by the best current interpretation of the Standard Model of particle physics with what could now be measured with increased precision.

The fundamental measurement of the Muon g-2 experiment (Source: D. Hertzog, APS April 2021)
The fundamental measurement of the Muon g-2 experiment (Source: D. Hertzog, APS April 2021)

In order to conduct this experiment, the Fermilab team included a very wide range of specialists from multi-disciplinary areas of physics.

A multi-disciplinary team of physicists was required (Source: D. Hertzog, APS April 2021)
A multi-disciplinary team of physicists was required (Source: D. Hertzog, APS April 2021)


Hertzog went over many of the instrumental design aspects and how the team had to reduce any sources of systematic errors.  He described how the magnetic field of the large rind had to be shimmed and adjusted so that any non-linearity or asymmetry in the magnetic field was very well controlled and known.

Reviewing all of the constraints on increasing precision  (Source: D. Hertzog, APS April 2021)
Reviewing all of the constraints on increasing precision  (Source: D. Hertzog, APS April 2021)


Finally, Hertzog showed us the form of the equation that included all of the details that had to be constrained or corrected in order to get the new and best estimate of the magnetic spin frequency.  So, even though I missed a lot of the details of the experiment, Hertzog let us in on some of the aspects.  Now we have to wait and see if this latest experiment, with good increased accuracy, but not quite the five sigma statistical results desired, will require new physics or not.  Stay tuned!

Some details that must be controlled for the g-2 experiment (Source: D. Hertzog, APS April 2021)
Some details that must be controlled for the g-2 experiment (Source: D. Hertzog, APS April 2021)



Until next time, here from our burrow, stay safe, as we recover more of our freedom,


Resident Astronomer George



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