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What is the lecture mainly about? What is the professor’s opinion about the newer muon detectors?
What is the lecture mainly about? What is the professor’s opinion about the newer muon detectors?
admin
2022-07-28
47
问题
What is the lecture mainly about?
What is the professor’s opinion about the newer muon detectors?
Listen to part of a lecture in an archeology class. (P =Professor, S = Student)
P: Talking about one popular myth in archeology, some people simply think excavation is digging the site until something valuable is found. Well, while there is an element of luck involved, we have an array of high tech devices to help us figure out where to put our efforts. You know, we can’t just dig up the site randomly looking for an ancient structure. There is one of the newer tools actually created by a different field of study. The machine relies on particle physics. Um… interdisciplinary I’d say. And it is called a muon detector, or counter. Muon is a charged elementary particle similar to electron. Okay, let me start over. On Earth, most naturally occurring muons are created by cosmic rays, which consist mostly of protons, many arriving from deep space at very high energy. When these charged particles of cosmic rays collide with molecules in the upper atmosphere, they break up into smaller particles, muons. Traveling at the speed of light, muons can penetrate tens of meters into rocks and other matter on Earth’s surface. In fact, they can pass through solid matter, so they can transmit deep into the surface. Thus, this property of muon is perfect for archeologists to take advantage of. Let me explain. Over the course of several months, one detector can build up a picture showing the shadows of structures they’re studying—like the Mayan pyramid in Central America, for example. Wecre interested in finding out if there are buried chambers or other rooms inside. Well, a muon detector can track a great number of muons passing through the less dense space inside the pyramid. Yes, you have your hand up?
S: I don’t think I get how this device works exactly.
P: Okay, well, when muons pass through… uh… say… stone walls of a pyramid, dense material, they lose energy. So, in the case of empty space, more muons can pass through because they lose less energy. The muon detector can identify the area by measuring the amount of muons in each place. We can see darker colors in empty spaces, so we wind up with a sort of… picture of the site and its internal structure.
S: Picture?
P: Yes, in the same way that CT scans produce a 3-D picture of your body using X-rays. It literally is like tomography in the medical sense.
S: Okay, so if darker areas show up inside the pyramid, we assume it’s an empty space with more muons.
P: You got it. This technology enables us to see what’s inside of the structure before we dig up the site. So, now we know exactly where to excavate, and we can minimize the damage. You know, even a little damage could result in losing crucial information forever. Now, it was when archeologists began to use muon detectors that they improved. Four decades ago, a physicist buried these detectors in the ground, surrounding the Egyptian pyramids. He was looking for buried chambers. However, he saw no surprises in that experiment. But he did demonstrate that the technique worked. One of the problems was that the machine he used was about the size of a water heater. It was so big that many archeologists doubted its practicality. Then, there was another issue of range. With the detector used in that time, we could only scan from muon directly above it but not from the sides. So, it actually had to be placed underneath the pyramid first, so we could look up into the inside of the ancient structure. It would be nice, for instance, to have a system that didn’t take six months to produce an image. I believe that’s way better than the year it took for this physicist’s study to get the results, but still… Well, there’s good reason to believe that with better equipment, we’re going to use muons in much more diverse manners. Muon detectors can also be used in other areas of science. For instance, to scope our nuclear waste sites or even look for the underground warning site in a volcanic eruption. Moreover, there are plenty of archeologists willing to try this device.
选项
A、She appreciates the help they provide even though it takes much time to produce images.
B、She is afraid that many archeologists will be unwilling to learn to use them.
C、She thinks that they have greater potential in areas of science other than archeology.
D、They provide more accurate information about the age of objects than older detectors did.
答案
A
解析
题目询问教授对新的介子探测器的看法。在讲座最后,教授提到,新的介子探测器比40年前的机器好了很多,成像用的时间更少。虽然她希望能够有一台不需要六个月便能成像的设备,但她认为新的介子探测器已经给考古带来了很多好处(It would be nice…to have a system that didn’t take six months to produce an image…but still…)。由此可见,A项正确。B项“她害怕很多考古学家会不愿意去学习使用它们的方法”与讲座提到的“有很多考古学家愿意尝试使用这种装置”的表述相反。C项“她认为它们在考古学以外的科学领域有更大的潜力”,教授在讲座中没有具体比较介子探测器在哪个领域应用更广,故不选C项。D项“它们比老一代的探测器更能提供准确的关于物体年代的信息”在讲座中没有被提及。
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