Halflife of Particles at Different Speeds?

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Discussion Overview

The discussion revolves around the effects of a particle's speed on its halflife, particularly focusing on neutrons and their behavior at relativistic versus non-relativistic speeds. Participants explore experimental approaches and theoretical implications related to particle lifetimes in different conditions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires whether the halflife of particles, specifically neutrons, changes when measured at relativistic speeds compared to non-relativistic speeds.
  • Another participant references a common example from introductory special relativity regarding muon lifetimes, suggesting that the topic is well-established in educational contexts.
  • A different participant describes methods for measuring the lifetimes of long-living particles like neutrons and muons, noting that muon lifetimes can be compared between stationary and moving states, with measurements aligning with theoretical predictions.
  • One participant mentions that current neutron lifetime measurements utilize ultracold neutrons, indicating a specific experimental approach to studying neutron behavior.

Areas of Agreement / Disagreement

Participants express varying levels of familiarity with the topic, and while some methods and examples are acknowledged, there is no consensus on the effects of speed on halflife or the feasibility of measuring neutrons at non-relativistic speeds.

Contextual Notes

The discussion highlights challenges in measuring halflife under different conditions, including the difficulty of slowing down free neutrons and the dependence on specific experimental setups.

LiteHacker
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Hello,

I am interested if anyone ever studied if a particle's halflife under different conditions.
Usually you can see how long a particle lasts by measuring how long it moves at a relativistic speed.

Has anyone ever tried to experiment and see if having the particle move at a relativistic speed would affect its halflife?

For example, the neutron is noted to have a halflife of 611.0 ± 1.0 s. I gather this was calculated by measuring the free neutron's distance traveled at a relativistic speed.

I do understand that it is very difficult to slow down a free neutron from a reaction, but has anyone ever tried to measure free neutron's halflife at a non-relativistic speed?
 
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For long-living particles like the neutron, the common method is to put a bunch of neutrons in a box and to measure the (time-dependent) activity.

Muon lifetimes can be measured with stopped muons (=> at rest in the lab frame) and compared with moving muons (from cosmic rays, or in particle collider experiments).

In particle colliders, the energy and therefore the gamma factor of the particle varies, therefore you can measure the predicted time dilation in a wide energy range with high precision. Needless to say that measurements agree with theory ;).
 
LiteHacker, According to Wikipedia, the best current measurements of the neutron lifetime are made using ultracold neutrons (about 7.6 m/s)
 

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