JHUAPL: MESSENGER Data Could End Neutron Lifetime Stalemate

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bystander
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JHUAPL: MESSENGER Data Could End Neutron Lifetime Stalemate

Post by bystander » Thu Jun 11, 2020 7:13 pm

MESSENGER Shows How a Spacecraft
Could End Neutron Lifetime Stalemate

Johns Hopkins University Applied Physics Laboratory | 2020 Jun 11
Neutrons aren’t a model of resilience when it comes to living a single life. Strip one from an atom’s nucleus and it will quickly disintegrate into an electron and a proton. But scientists can’t determine how quickly, despite decades of trying, and that’s problematic because knowing that lifetime is key to understanding the formation of the elements after the Big Bang.

Now, a team of researchers ... has provided a way that could end the decades-long stalemate. Using data from NASA’s MESSENGER spacecraft, the team shows that the lifetime of a neutron can be measured from space. ...

Since the early 1990s, scientists have disagreed about how long lone neutrons last, mainly because the two methods used so far give highly precise results that don’t line up.

The “bottle” method traps neutrons in a bottle and tracks how long they take to radioactively decay, which on average is around 14 minutes and 39 seconds. The “beam” technique instead fires a beam of neutrons and tallies the number of protons created from radioactive decay. On average, this takes about 14 minutes and 48 seconds — nine seconds longer than the bottle method.

Nine seconds isn’t much, but relative to the uncertainty in either method’s measurements — at most two seconds — it’s enormous. ...

First Space-Based Measurement of Neutron Lifetime
Durham University, UK | 2020 Jun 11

Pinning Down a Neutron’s Lifetime
APS Physics Synopsis | 2020 Jun 11

Space-Based Measurement of the Neutron Lifetime Using Data from the
Neutron Spectrometer on NASA’s MESSENGER Mission
~ Jack T. Wilson et al
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Re: JHUAPL: MESSENGER Data Could End Neutron Lifetime Stalemate

Post by saturno2 » Thu Jun 11, 2020 9:27 pm

" The team shows that the lifetime of a neutron
can be measured from space"
Very interesting

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Re: JHUAPL: MESSENGER Data Could End Neutron Lifetime Stalemate

Post by neufer » Thu Jun 11, 2020 10:05 pm

bystander wrote: Thu Jun 11, 2020 7:13 pm
MESSENGER Shows How a Spacecraft
Could End Neutron Lifetime Stalemate

Johns Hopkins University Applied Physics Laboratory | 2020 Jun 11
Click to play embedded YouTube video.
Since the early 1990s, scientists have disagreed about how long lone neutrons last, mainly because the two methods used so far give highly precise results that don’t line up.

The “bottle” method traps neutrons in a bottle and tracks how long they take to radioactively decay, which on average is around 14 minutes and 39 seconds. The “beam” technique instead fires a beam of neutrons and tallies the number of protons created from radioactive decay. On average, this takes about 14 minutes and 48 seconds — nine seconds longer than the bottle method.

Nine seconds isn’t much, but relative to the uncertainty in either method’s measurements — at most two seconds — it’s enormous. ...
Art Neuendorffer

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Re: JHUAPL: MESSENGER Data Could End Neutron Lifetime Stalemate

Post by BDanielMayfield » Sat Jun 13, 2020 2:48 pm

Might the trapped neutron rate be the true rate of decay while the fired beam neutrons are lasting slightly longer because outside observers are seeing a relativistic time dilation effect?

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Re: JHUAPL: MESSENGER Data Could End Neutron Lifetime Stalemate

Post by neufer » Sat Jun 13, 2020 3:50 pm

BDanielMayfield wrote: Sat Jun 13, 2020 2:48 pm
Might the trapped neutron rate be the true rate of decay

while the fired beam neutrons are lasting slightly longer
because outside observers are seeing a relativistic time dilation effect?
Beams of 940 MeV rest mass neutrons tend to be highly NON relativistic
[to the point where old fashioned mechanical slots
(a la Galileo) are used for velocity discrimination]:
https://en.wikipedia.org/wiki/Neutron_temperature wrote:

Code: Select all

Neutron energy 	Energy range
............................................
0.0–0.025 eV 	Cold neutrons
0.025 eV 	Thermal neutrons
0.025–0.4 eV 	Epithermal neutrons
0.4–0.5 eV 	Cadmium neutrons
0.5–1 eV 	EpiCadmium neutrons
1–10 eV 	Slow neutrons
10–300 eV 	Resonance neutrons
300 eV–1 MeV 	Intermediate neutrons
1–20 MeV 	Fast neutrons
> 20 MeV 	Ultrafast neutrons 
Art Neuendorffer

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