月度暗物质的背景补充阅读

killerinJP

认真研读了一下还是一知半解的，想问lz这题目是从哪里弄的？
我大概做了一下，请tx们讨论，我做的答案：CCADE,AEED。
Open to discuss~

-- by 会员 rebecca_wang (2010/9/30 3:23:30)

我的答案是CCADE AEDD 和你的有点不一样啊。。
第8题我选D，原文说了：The detecting medium is the seawater itself: when a neutrino interacts with a (40)particle in an atom of seawater. the result is a cascade of electrically charged particles and a flash of light that can be detected by the sensors.

-- by 会员 s19870117 (2010/9/30 15:21:10)

http://forum.chasedream.com/GMAT_Math/thread-488934-1-1.html?userid=-1&extparms=ThreadCatalogID%3d48%26page%3d1

答案 第一题和最后一题 是c

kking

我震惊了...膜拜..

ryangu619

这个强 顶！！！！

ryangu619

=============杨继里面的文章我给你编辑一下格式吧=======================

Virtually everything astronomers known about objects
outside the solar system is based on the detection of
photons-quanta of electromagnetic radiation. Yet there
is another form of radiation that permeates the universe:
(5) neutrinos. With (as its name implies) no electric charge,
and negligible mass, the neutrino interacts with other
particles so rarely that a neutrino can cross the entire
universe, even traversing substantial aggregations of
matter, without being absorbed or even deflected. Neutrinos
can thus escape from regions of space where light
and other kinds of electromagnetic radiation
are blocked by matter. Furthermore, neutrinos carry with them
information about the site and circumstances of their
production: therefore, the detection of cosmic neutrinos
(15)could provide new information about a wide variety of
cosmic phenomena and about the history of the universe.
But how can scientists detect a particle that interacts
so infrequently with other matter? Twenty-five years
(20)passed between Pauli’s hypothesis that the neutrino
existed and its actual detection: since then virtually all
research with neutrinos has been with neutrinos created
artificially in large particle accelerators and studied
under neutrino microscopes. But a neutrino telescope,
(25) capable of detecting cosmic neutrinos, is difficult to
construct. No apparatus can detect neutrinos unless it is
extremely massive, because great mass is synonymous
with huge numbers of nucleons (neutrons and protons),
and the more massive the detector, the greater the pro-
(30) bability of one of its nucleon’s reacting with a neutrino.
In addition, the apparatus must be sufficiently shielded
from the interfering effects of other particles.
Fortunately, a group of astrophysicists has proposed
a means of detecting cosmic neutrinos by harnessing the
(35) mass of the ocean. Named DUMAND, for Deep Under-
water Muon and Neutrino Detector, the project calls for
placing an array of light sensors at a depth of five kilo-
meters under the ocean surface. The detecting medium is
the seawater itself: when a neutrino interacts with a
(40)particle in an atom of seawater. the result is a cascade of
electrically charged particles and a flash of light that can
be detected by the sensors. The five kilometers of sea-water
above the sensors will shield them from the interfering
effects of other high-energy particles raining down
(45) through the atmosphere.
The strongest motivation for the DUMAND project
is that it will exploit an important source of information
about the universe. The extension of astronomy from
visible light to radio waves to x-rays and gamma rays
(50) never failed to lead to the discovery of unusual
objects such as radio galaxies, quasars, and pulsars. Each of
these discoveries came as a surprise. Neutrino astronomy
will doubtless bring its own share of surprises.

谷雨书