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Thu Apr 25, 2019, 02:33 AM

Dark Matter Hunter Captures The 'Rarest Thing Ever Recorded' In A Process 1 Trillion Times Longer Th

Dark Matter Hunter Captures The ‘Rarest Thing Ever Recorded’ In A Process 1 Trillion Times Longer Than The Age Of The Universe
24 April 2019, 11:55 pm EDT By Naia Carlos Tech Times

The universe is more than 13 billion years old. Multiply this number by a trillion and that is the half-life of a xenon-124 atom, which is the time it takes for a group of xenon-124 to diminish by half.

For the first time ever, scientists were able to observe this decaying process in a near-impossible feat.

"We actually saw this decay happen. It's the longest, slowest process that has ever been directly observed, and our dark matter detector was sensitive enough to measure it," said Ethan Brown, coauthor and an assistant professor of physics at Rensselaer Polytechnic Institute, in a report from the university. "It's an amazing to have witnessed this process, and it says that our detector can measure the rarest thing ever recorded."

Amazingly, the scientists were able to pull it off using an instrument that's designed to search the universe for another elusive sight: dark matter.

More:
https://www.techtimes.com/articles/242225/20190424/dark-matter-hunter-captures-the-rarest-thing-ever-recorded-in-a-process-1-trillion-times-longer-than-the-age-of-the-universe.htm

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Reply Dark Matter Hunter Captures The 'Rarest Thing Ever Recorded' In A Process 1 Trillion Times Longer Th (Original post)
Judi Lynn Apr 2019 OP
tblue37 Apr 2019 #1
3sam3 Apr 2019 #2
magicarpet Apr 2019 #3
3Hotdogs Apr 2019 #4
lastlib Apr 2019 #5
lastlib Apr 2019 #6
eppur_se_muova Apr 2019 #7
cstanleytech Apr 2019 #8
eppur_se_muova Apr 2019 #9
cstanleytech Apr 2019 #10
eppur_se_muova Apr 2019 #11
cstanleytech Apr 2019 #12
eppur_se_muova Apr 2019 #13
cstanleytech Apr 2019 #14

Response to Judi Lynn (Original post)

Thu Apr 25, 2019, 02:35 AM

1. Wow. Just wow. K&R. nt

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Response to Judi Lynn (Original post)

Thu Apr 25, 2019, 04:50 AM

2. Rensselaer an awesome school

An friend of my brother's Math genius daughter is working on her PHD there. She's in her 2nd year as a student and started when she was 15! They make wonderful accommodations for underage students. She's a popular teacher too. FYI. I don't think they have a football team.



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Response to Judi Lynn (Original post)

Thu Apr 25, 2019, 05:31 AM

3. No football team,... I bet they have a killer chess club.

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Response to Judi Lynn (Original post)

Thu Apr 25, 2019, 06:26 AM

4. Fuck. That ain't nuthin. Ya wanna see slow?

Watch my employees get up off a chair when you ask them to do somthin'.

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Response to Judi Lynn (Original post)

Thu Apr 25, 2019, 06:51 AM

5. Wow!

I f*cking love science! This is beyond cool!

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Response to Judi Lynn (Original post)

Thu Apr 25, 2019, 06:52 AM

6. Is this rarer than tRumpolini complying with a subpoena?

(asking for a friend.....)

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Response to Judi Lynn (Original post)

Thu Apr 25, 2019, 10:46 AM

7. Interesting -- this is a double electron-capture decay.

It was only in 1987 that the first instance of double-beta (electron emission) decay was observed, with t1/2 ~ 1.1 x 10^20 y. That's more than a hundred times faster than the process described here.

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Response to Judi Lynn (Original post)

Thu Apr 25, 2019, 10:58 AM

8. If it takes that long to decay how could they observe it at all given the current age

of the universe?

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Response to cstanleytech (Reply #8)

Thu Apr 25, 2019, 11:09 AM

9. 124 grams of Xe-124 contains 6E23 atoms ...

So in one year, i.e. about 1 / 10^22 half-life, you should expect several dozen atoms to decay. If your detectors are very sensitive and heavily shielded, you can pick up each of these decays as an individual event.

Ain't technology wonderful ?

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Response to eppur_se_muova (Reply #9)

Thu Apr 25, 2019, 04:37 PM

10. Still not getting it, sorry.

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Response to cstanleytech (Reply #10)

Thu Apr 25, 2019, 05:32 PM

11. OK. There are LOTS and LOTS of atoms ... ;)

Even if it's very unlikely that any one atom will decay at any given time, and it will take Brazillions of years for all to decay, if the sample is large enough and your instruments sensitive enough you can monitor a sample for months and get enough recorded decay events to extrapolate the half-life -- the longer you take measurements, the more precise the extrapolation. Also, the larger your sample, the faster you accumulate data -- these guys used 3,200 kg of liquid xenon. They should have observed a pretty large number of decay events -- enough to lower the statistical uncertainty pretty quickly. Oh, and placing the experiment inside a mountain helped shield the detectors from cosmic rays and other background radiation.

(In small amounts, Xe costs ~ $1.20/g, or $1200/kg, for anyone who's thinking of repeating this experiment.)

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Response to eppur_se_muova (Reply #11)

Thu Apr 25, 2019, 05:38 PM

12. No, I mean if they say it takes a long time to decay why are they even seeing

any at all currently?

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Response to cstanleytech (Reply #12)

Fri Apr 26, 2019, 08:37 AM

13. The actual time for any atom to decay is random; *averaging* these times gives you the half life.

It is impossible to predict when any particular atom will decay; only a statistical effect can be observed. But in any reasonably long time interval, there will be *some* atoms decaying -- it just takes a few tens of sextillions of years for this to accumulate to the point where as many as half have decayed. But a few months should be adequate to measure the rate of decay, vs a few seconds for more typical short half-lives.

https://en.wikipedia.org/wiki/Half-life#Probabilistic_nature describes it very well.

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Response to eppur_se_muova (Reply #13)

Fri Apr 26, 2019, 01:35 PM

14. Oh, ok I think I get it now.........barely of course :)

Thank you.

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