I read this novel about 10 years ago, but it was a library book, already used. But it did not “feel” like an old classic. Hard to pinpoint the time it was written.
What I remember best is the book. There was only one story in it, so a novel, not a novella, but a rather short one. Indeed the book was very narrow, a hardcover with the two rather thick covers making up almost half the width (well this may be an exaggeration of my memory, maybe not "almost half" the width but a bit less, but a non-negligible part). The cover was mostly dark blue.
It is about a scientific team trying to reach the “absolute zero”, 0 K, a big project, scores of scientist and techs.
It is told by the point-of-view character who is related to the person in charge of the project. Not as close as his brother but possibly his brother-in-law, but I am not sure.
The project suffers many problems, delays, and so on. At the end the person in charge decides to go on despite a known danger. Absolute zero is indeed achieved, but a disaster occurs. It is not as simple as an explosion who’d kill everyone on site. It is in a sense worse.
The POV character was not on-site so he survives. But one thing I remember is that he wonders whether all the people who were on-site are really dead or still living in some different world that cannot communicate with his, in a kind of suspended animation at zero temperature or something like that.