Reading Comprehension

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: 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 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 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, 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 probability 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 mass of the ocean. Named DUMAND, for Deep Underwater Muon and Neutrino Detector, the project calls for placing an array of light sensors at a depth of five kilometers under the ocean surface. The detecting medium is the seawater itself: when a neutrino interacts with a 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 seawater above the sensors will shield them from the interfering effects of other high-energy particles raining down 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 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.



1. Which of the following titles best summarizes the passage as a whole?
(A) At the Threshold of Neutrino Astronomy
(B) Neutrinos and the History of the Universe
(C) The Creation and Study of Neutrinos
(D) The DUMAND System and How It Works
(E) The Properties of the Neutrino

IMo A

please explain why not B?
My reasoning that history is not mentioned as such so B might be wrong..
In A Does threshold means the peak of Neutri... astronomy?? please explain how threshold is the right word here??

ketkoag wrote:please explain why not B?
My reasoning that history is not mentioned as such so B might be wrong..
In A Does threshold means the peak of Neutri... astronomy?? please explain how threshold is the right word here??

Answer is A.

Threshold means 'the first step' or 'at the doorway'. Since the passage introduces "...another form of radiation that permeates the universe...", so threshold is a good word to describe.

B states "....history of the universe" which is beyond the passage scope.

thanks a bunch..

whats the problem with (C) Please explain

Mayur Sand wrote:whats the problem with (C) Please explain

there is no mention of how a nutrino could be created !! hence C is out.

I would go for A.

Had chosen A too for the above problem.

now have a look at the below marked question


8. According to the passage, the interaction of a neutrino with other matter can produce
(A) particles that are neutral and massive
(E) contrast the motivation of earlier astronomers with that of the astrophysicists working on the DUMAND project
(B) a form of radiation that permeates the universe
(C) inaccurate information about the site and circumstances of the neutrino's production
(D) charged particles and light
(E) a situation in which light and other forms of electromagnetic radiation are blocked

I mark my folly in choosing B over D as the correct answer.