p***a
发帖数: 20 | 1
中微子的发现有年头了，不过以前都认为中微子的质量为零，
所以实验上给的都是中微子质量的上限，电子中微子质量小于
几个eV(电子伏)，muon中微子质量小于0.17MeV,tau中微子质量小于
24MeV，想想电子的质量是0.511MeV,质子的质量是0.938GeV,
可以说这些中微子质量都很小．
98年日本说发现了中微子＇振荡＇，间接证明了中微子有静
质量，但是现在还没有被广泛的接受，还在观察中．
如果中微子有静质量，那是个大事情，因为中微子只有弱作用，
基本上产生了就很难消灭，那整个宇宙的质量可能就大部分
落在中微子身上．．．．．． | p******e
发帖数: 58 | 2
(sorry, this might be too late. )
I should say, there's no final words on it yet.
The current model (also a widely accepted one) requires
neutrino mass = 0. However, many are still thinking of
the possibility of none 0 mass.
There are a few hints from experiment, that may suggests
neutrino mass. One is from solar neutrino, one get quite
different results from what we expect. The expectation
is coming from 1.particle model + 2.sun model. If we are
confident enough on 2, or different 2 can no | p******e
发帖数: 58 | 3 As far as I understand, the super long tunnle is not necessary.
As I mentioned before, some accelerater experiments are under consideration.
The one you mentioned might be one of them. They are usually have the
following setting.
1. Produce neutrino beam on an accelerater. In the case you mentioned, it
is likely that the beam is produced at Fermilab in Chicago.
2. Direct the beam to a target detector far away. So Minnesota might be
the place where the detector sits.
The reason for no tunnle n | a****y
发帖数: 1035 | 4 多谢!! 多谢!!
多年以前我从一本书里见到关于SN1987(如果没记错的话)的中微子观测结果. 除了一
个观测站的结果早了若干小时外, 其它好几个观测站的结果都是同步的.有一个站提前
报告了结果, 这个情况解释为造假或偶然 似乎都不通.
前些时候关于中微子振荡的报道也只是来自一个实验室, 对吧. 所以在该版贴了这个
问题, 想听听诸位大侠的高见.
BTW, 质子衰变观测到了没有?
【在 p******e 的大作中提到】
: As far as I understand, the super long tunnle is not necessary.
: As I mentioned before, some accelerater experiments are under consideration.
: The one you mentioned might be one of them. They are usually have the
: following setting.
: 1. Produce neutrino beam on an accelerater. In the case you mentioned, it
: is likely that the beam is produced at Fermilab in Chicago.
: 2. Direct the beam to a target detector far away. So Minnesota might be
: the place where the detector sits.
: The reason for no tunnle n
| f*******d
发帖数: 339 | 5
What they are comparing are not upgoing and down going neutrinos,
(the upgoing neutrinos are very few), but rather mu neutrinos and
e neutrinos, these should have a ratio of 2:1, but experiment found
the ratio less than that. Also, no one has ever detected tau neutrinos
directly yet.
The trouble is, although solar neutrino,atomspheric neutrino and collider
experiment (LSND, and the future Chicago-Minnesota project)all show
neutrino oscillation, the results are inconsistent. To help solve this
【在 p******e 的大作中提到】
: As far as I understand, the super long tunnle is not necessary.
: As I mentioned before, some accelerater experiments are under consideration.
: The one you mentioned might be one of them. They are usually have the
: following setting.
: 1. Produce neutrino beam on an accelerater. In the case you mentioned, it
: is likely that the beam is produced at Fermilab in Chicago.
: 2. Direct the beam to a target detector far away. So Minnesota might be
: the place where the detector sits.
: The reason for no tunnle n
| p******e
发帖数: 58 | 6
Sorry, I made quite a few mistakes. I read the Super Kamiokanda paper
last year, so can not remember it clearly.
I re-read the paper again, and make corrections here:
The experiment made two major measurements,
1.the atmospheric neutrino flux ratio nu(mu)/nu(e)
the ratio from experiment R(data)
the ratio from expectation R(MC)
R(data)/R(MC) = 0.66 +- 0.06(stat.) +- 0.08(sys.)
while we expect one if agreement were abserved.
2.the ratio of upward to downward mu like events (so not
【在 f*******d 的大作中提到】
:
: What they are comparing are not upgoing and down going neutrinos,
: (the upgoing neutrinos are very few), but rather mu neutrinos and
: e neutrinos, these should have a ratio of 2:1, but experiment found
: the ratio less than that. Also, no one has ever detected tau neutrinos
: directly yet.
: The trouble is, although solar neutrino,atomspheric neutrino and collider
: experiment (LSND, and the future Chicago-Minnesota project)all show
: neutrino oscillation, the results are inconsistent. To help solve this
| f*******d
发帖数: 339 | 7
Now it is believed that only two labs detected neutrino from 1987A (at the
same
time), the other lab's problem is that their reported signal
is at the edge of their detection energy threshold so it is unreliable.
Super Kamionkande is not the only lab detecting neutrino oscillation.
Earlier,
the same signal is also detected, but the data is not good enough, also
at that time the water based detectors detect this signal, but iron based
detectors don't, so there were questions on the reliability.
【在 a****y 的大作中提到】
: 多谢!! 多谢!!
: 多年以前我从一本书里见到关于SN1987(如果没记错的话)的中微子观测结果. 除了一
: 个观测站的结果早了若干小时外, 其它好几个观测站的结果都是同步的.有一个站提前
: 报告了结果, 这个情况解释为造假或偶然 似乎都不通.
: 前些时候关于中微子振荡的报道也只是来自一个实验室, 对吧. 所以在该版贴了这个
: 问题, 想听听诸位大侠的高见.
: BTW, 质子衰变观测到了没有?
| f*******d
发帖数: 339 | 8
Standard Model did not say proton would decay!
【在 a****y 的大作中提到】
: 多谢!! 多谢!!
: 多年以前我从一本书里见到关于SN1987(如果没记错的话)的中微子观测结果. 除了一
: 个观测站的结果早了若干小时外, 其它好几个观测站的结果都是同步的.有一个站提前
: 报告了结果, 这个情况解释为造假或偶然 似乎都不通.
: 前些时候关于中微子振荡的报道也只是来自一个实验室, 对吧. 所以在该版贴了这个
: 问题, 想听听诸位大侠的高见.
: BTW, 质子衰变观测到了没有?
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