Missing Neutrons May Lead a Secret Life as Dark Matter

Neutrons shouldn’t be all that mysterious. Found inside every atomic nucleus, they may seem downright mundane—but they have long confounded physicists who try to measure how long these particles can live outside of atoms.
For more than 10 years researchers have tried two types of experiments that have yielded conflicting results. Scientists have struggled to explain the discrepancy, but a new proposal suggests the culprit may be one of the biggest mysteries of all: dark matter.

Scientists are pretty sure the universe contains more matter than the stuff we can see, and their best guess is that it takes the form of invisible particles.
What if neutrons are decaying into these invisible particles? This idea, put forward by University of California, San Diego, physicists Bartosz Fornal and Benjamin Grinstein in a paper posted this month to the physics preprint site arXiv.org, would explain why one type of neutron experiment consistently measures a different value than the other.
If true, it could also provide the first way to access the dark matter particles physicists have long been seeking to no avail.

Dark Matter Interpretation of the Neutron Decay Anomaly
http://arxiv.org/abs/1801.01124

続く

The idea has already gripped many researchers making neutron lifetime measurements, and some have quickly scrambled to look for evidence of it in their experiments. If neutrons are turning into dark matter, the process could also produce gamma-ray photons, according to Fornal and Grinstein’s calculations.
“We have some germanium gamma-ray detectors lying around,” says Christopher Morris, who runs neutron experiments at Los Alamos National Laboratory.
By serendipity, he and his team just recently installed a large tank to collect neutrons on their way from the start of the experiment to the point where physicists try to measure their lifetimes.
This tank provided a large holding cell where many neutrons might decay into dark particles, if the pOnly one of the two types of neutron decay experiments would be sensitive to neutrons decaying into dark matter.
This type, called “bottle experiments,” essentially puts a given number of neutrons into a “bottle” with magnetic walls that holds them inside, then counts how many are left after a certain amount of time.
Through many measurements the researchers can calculate how long an average neutron lives.

The other type of experiment looks for the main product of neutron decays.
Through a well-known process called beta decay, a neutron outside of an atomic nucleus will break down into a proton, an electron and an antimatter neutrino. So-called “beam” experiments shoot a beam of neutrons into a magnetic trap that catches positively charged protons.
Researchers count how many neutrons go in and how many protons come out after a given time, then infer the average time it takes a neutron to decay.

つづく

Both classes of experiments find neutrons can last for only about 15 minutes outside of atoms.
But bottle experiments measure an average of 879.6 seconds plus or minus 0.6 second, according to the Particle Data Group, an international statistics-keeping collaboration.
Beam experiments get a value of 888.0 seconds plus or minus 2.0 seconds. The 8.4-second difference may not seem like much, but it is larger than either of the calculations’ margins of error—which are based on the experimenters’ understanding of all the sources of uncertainty in their measurements.
The difference leaves the two figures with a statistically significant “4-sigma” deviation. Experimenters behind both methods have scoured their setups for overlooked problems and sources of uncertainty, with no luck so far.

But if neutrons can transform in more ways than just beta decay, it would explain why bottle and beam experiments do not find the same answers.
Fornal and Grinstein suggest that occasionally neutrons turn into some type of dark particle, undetectable by traditional means.
The bottle experiments would then measure a slightly shorter lifetime for the neutron than beam experiments, because the former would be counting the dark matter decays in addition to the beta decays—and thus detecting a larger number of total decays in any given time period.
The beam setup, however, only measures how long it takes neutrons to turn into protons, so their tally would not include dark matter decays and would therefore suggest neutrons can stick around slightly longer.
And that is indeed what the two methods show.rocess in fact occurs, and produce gamma-rays as a by-product.
“When we heard about this paper, we took our detector and set it up next to our big tank and started looking for gamma rays.”
He and his team are still analyzing the results of this trial, but hope to have a paper out in a few weeks reporting on what they found.

この続きはリンクから
http://www.scientificamerican.com/article/missing-neutrons-may-lead-a-secret-life-as-dark-matter/

なるほど、そういうことか。

ツービーコンチヌエド

>>1-2
ふーん、へえ、わかったわかった

それがどうした

>>1
日本語でOK

ふーん、そういうことね。完全に理解した。

ちゃんと計算してあるな
角度とか

理解した。

英語はわかりやすい

　
うむ、ダーク股ーか
まるで準ゴーカン揉み消してもらった男だな
　

スレタイの日本語が崩壊している

またまた

なるほど…まったく分からん！

以前なんでもプラズマのせいにするのが流行ったけど、最近はなんでもダークマターのせいにするのが流行ってる

トイレによく「ダークマター」がこびりついてる。　

「フォースの韓国面に落ちた」なｗ

なぁんだそういうことだったのかー

流れがν速と同じでﾜﾛﾀw

ここまでダークコンドルなし
知らないとヤバイよ

助詞がおかしい

ダークマター 　　　　未知の素粒子

ダークエネルギー　　実態は二次元である世界をホログラフィック三次元投影して生じている見せ掛けの力

誰かブラックサンダーで例えてくれ。

中二病が喜びそうだな

誰か時間が止まるAV で例えてくれ

>>26
「これはまさに、言わばブラックサンダースフライドチキンである、というわけでございます」

日本語訳が出てからスレ立てしてくれ

中性子がすべてベータ崩壊するなら、どんな実験でも中性子寿命は同じはずなのに、
実験によって8.4秒も差が出る、これはベータ崩壊以外の変化が起こってるに違いない、
ってこと？

ベータ崩壊以外の何かがある！ → ダークマターへの転生だ！
ってのはちょっと性急な気がするが。

つまり
水素＞＞恒星＞＞超新星爆発＞＞中性子星＞＞ダークマター＞＞ダークエネルギー
こう言う順番でエントロピーが増大する訳だな

ありまぁす論文か
ロスアラモスで磁気瓶使ってやったってのは素人の科学ファンでも読めたけど
正体不明な物質に逃げるのはそこからの論理の拡大を隠してるかんじがする

とはいえ、正体不明の素粒子に逃げて名付けられたのがニュートリノで、
だいぶ経ってから存在が確認されたという成功実績が過去にあるからなぁ。

言っとけば世紀の大発見として名が残るかも知れない。
検証には1000年位掛かりそうだけど、知ったこっちゃねぇ。

こんな感じか？

こういう場合、
星の生成にもダークマターが使われてる
見かけの星間ガスよりも大きい星が誕生しているはず
オリオンのトラペジウムに結果が出るのは10万年後

転生したらダークマターだった

中性子星みたいにブラックホール崩壊しているんだろうとしている

チェレンコフ光である

で、ダークマターってなんなんだよ

あーそういうことね、完全に理解した

http://translate.google.co.jp/translate?sl=auto&tl=ja&js=y&prev=_t&hl=ja&ie=UTF-8&u=https%3A%2F%2Fwww.scientificamerican.com%2Farticle%2Fmissing-neutrons-may-lead-a-secret-life-as-dark-matter%2F&edit-text=&act=url

志村妙の卵焼き

少し調べてみたけど日本でもJ-PARKって施設で寿命の測定やってるみたい。
そこの結果が出てからじゃないとなんとも言えないのでは。

また、また～

仮にこれが実証されるとノーベル賞は言い出しっぺのこの人が優先されるのかな
貢献度も加味されるけど基本的に早い者勝ちだし

>>40
俺の股間の巨大な何かだぜ

あれだ、暗黒製粉って奴だな

単にビームのほうの相対論的時間の遅れを計算し忘れただけだったりして