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detected, and therefore increase the statistics of meaning of this second peak is unclear, as it is not
the experiment in a shorter operation time. There
would be complications however, of operating in
an open space, since the PMT coupled to the
scintillator needs to be connected to an H.V supply,
and the output signal needs to be sent to the circuit
for its processing; not to mention the considerations
needed to be made regarding the weather.
Another important aspect was the resolution of
the MCA employed to register the decay times.
From the calibration, only time intervals up to 5
could be measured. A consideration to be had for
future reproductions of this experiment, is that the
resolution of the MCA can limit the accuracy of the
measurements. In this case, there was a noise
present towards the beginning of the spectrum that
had to be removed manually from the data before
it was used for the curve fit.
One way to give continuity to this work, would be
to perform a similar experiment, detecting muons
with scintillators, but in different places with a
noticeable altitude difference. This would allow to
compare the amount of muons detected in each
case, and the difference of particles detected
would correspond to the ones that decayed when
going from one altitude to the other. Knowing the
velocity of the particles, it would be possible to
calculate the mean lifetime of moving muons.
These results could be compared with the ones
presented here and used to study relativistic effects
like time dilation.
B. Muon’s speed
7
8
The value = 2.400 × 10 ± 1.47 × 10 / ,
obtained for the mean speed of the muons using
the mean time intervals for the = 50 and
1
= 100 separations, is physically consistent
2
with special relativity, as the muon, being a massive
particle, it cannot travel faster than the speed of
light, but because it was generated in the upper
atmosphere by cosmic rays, their velocity must be
8
close to 3 × 10 / .
Nevertheless, there were some noticeable
problems with the time distributions. Towards the
right end of both of the original spectrums, a small
peak can be distinguished. Despite being small
compared to the peak used to adjust the gaussian
curve, it was always present in the measurements
for all the separation distances. The origin or
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Tlahuizcalli ISSN: 2448-7260
certain if there was something in the experimental
setup that could be responsible for it.
In addition to this, the left ends of the distributions
seem to have considerably more counts than the
right ends, so it may have a correlation with how
small the mean time is. Also, just like in the mean
lifetime experiment, there was a noise present
towards the beginning of the spectrum, so we
needed to apply a large enough delay to the
signals, in order to keep them away from that noise.
These effects distorted the distributions, making
them less gaussian, and therefore harder to fit. This
is what made the identification and subtraction of
the background necessary.
One way to continue this project, would consist on
performing the same experiment but under
different conditions, maybe even using different
detectors and electronics. The purpose would be
to identify if some of the effects mentioned here,
like the second peak on the right end of the
spectrum, are still present. This could help to
determine their origin and nature.
Finally, it is important to highlight that, just like the
mean lifetime experiment, the detectors were
placed inside a laboratory on the ground level of a
building. Moreover, the upper scintillator was
located just under a lamp (see fig.(8)). Despite the
lamp remaining off during the entirety of the
experiment, there could be associated effects that
we didn't consider.
V. Conclusions
The two values obtained for the mean lifetime of
the muon, with different PMT operating voltages,
were consistent with the reported value in the
Review of Particle Physics, within a 3 range. The
value calculated for the mean speed of the cosmic
ray muons, was consistent with special relativity.
In the mean lifetime experiment, a background
was present in the time distributions, so it had to be
measured and considered to get a correct value
of the mean lifetime. The origin of this background
is still unclear.
There were effects observed in the time
distributions for the muon's speed experiment, that
could not be fully explained, like the presence of a
Año 10 Núm. 30 septiembre-diciembre 2024