Nishina Program Day 3: Nuclear Physics, Detectors, and Oscilloscopes

Today marks the third day of the Nishina Program. Our day started off with a dive into modern nuclear physics. Dr. Ogawa explained the “Magic Numbers” in nuclei: 2, 8, 20, 28, 52, 82, and 126. When a nucleus contains one of these numbers of protons or neutrons, it becomes especially stable compared to nuclei of similar size. For example, Calcium, which has 20 protons and (usually) 20 neutrons, has another stable isotope with 28 neutrons, but few in between. Similarly, Lead, with 82 protons and 126 neutrons, is stable, but a Bismuth atom with 83 protons and 125 neutrons is radioactive. Amazingly, these “Magic Numbers” are actually not magical at all; they actually arise from quantum mechanical implications and mathematics. It is such a beautiful thing that quantum mechanics and math work in this manner. With those, nuclear physics phenomena become so much more elegant and awespiring.

Another highlight of the morning lecture were the drop lines for protons and neutrons. In the periodic table, all naturally-occuring and artificially created elements and isotopes fall within a strict band. Elements closer to the center of the band are more stable and elements at the periphery almost instantaneously disintegrate. As Dr. Ogawa explained, this arises from a formula for nuclear binding energy, which measures how strongly the nucleus is bound. Because of the nature of the formula, any nucleus found with too many protons to be in the drop line will gain binding energy if it loses a proton, making it extremely unstable – so extreme that it will not be found in nature. This explains why all created nuclei lie within the drip lines; everything on the outside will instantly disintegrate.

Secondly, we received a lecture on detectors from Professor Sako. He highlighted three methods of radiation detection: ionization, scintillation, and chemical change. While I would love to write about every one of them, I must save my words by only writing about the highlights of scintillation. Scintillation detectors convert radiation into light, which is then amplified and detected through a light detector. Because radiation is often hard to detect, scientists often have to resort to unconventional methods. This brings me to a greater point. Professor Sako announced that, “innovation in detectors can lead to new science.” This statement rings especially true, for there are so many phenomena that we would love to detect, like gravitational waves or cosmic strings, but our detectors are just not good enough to handle them. Science can only progress as far as detectors, just like one’s ability to measure length is limited by the quality of one’s ruler. The human eye was superseeded by optical microscopes that opened up the cellular and microscopic world. Then optical microscopes gave way to electron microscopes, which allowed us to peer directly at atoms. And so on and so forth. It would be my dream to create a device that could open up new avenues for human progress….

But back to reality. We had more time with the oscilloscope. However, we spent less time on training and more time on application. We were actually able to measure the speed of electric currents using the oscilloscope and different lengths of wire. As part of Team Ion, I am able to say that we exhibited a strong group cohesion. Everybody’s work complimented each other and we all helped each other when needed. Our results were shocking. Electric currents travel at 65% of the speed of light! That speed seem so fast that it feels almost instantaneous, but it is important to remember its finite speed. Whenever we need precise measurements in time, we must remember even these few nanoseconds. We are now aware to take this precaution whenever setting up experiments; it can make a huge difference in our results.

Team Ion works the oscilloscope.
Team Ion works the oscilloscope.
Dr. Kishida demonstrating a new feature to the students.
Dr. Kishida demonstrating a new feature to the students.


While Arianna went off with her friend, the Saltmans and I meandered towards Shinjuku in search of a sushi restaurant. And when I say meandered, I actually mean meandering. We hopped from one side of Shinjuku to the other, for that sushi restaurant was impossible to find, having moved from its original location and incorrectly displayed its new location. Along the way, I snapped this picture of Japan’s Empire State Building near its own “Times Square.”

Empire State Building?

Eventually, we settled in an Okonomiyaki place. Okonomiyaki is a Japanese cook-it-yourself pancake. However, this pancake is much more than just batter. We ordered one with mushrooms, lettuce, and a slew of other vegetables and another one with various seafood. In the center of the table lay a flat stove, and after mixing the batter, we cooked the pancake right on the tabletop stove, allowing us to smell the savory aromas and hear the sizzling of oil right in front of us. All I can say is that I have never tasted vegetables that yummy, and that I regret not taking any pictures. I’ll go ask Mrs. Saltman for some. But for now, bye!

July 29, 2015

~Jeffrey Qiao


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