Hi

my name is Ho San

I am an experimental physicist looking for new challenges.
On top of what I know, I want to learn and create.

I made this website to share who I am, what I do, and because why not.

I am planning to update this website whenever I have something to share.

For today, I would like to share my current ongoing music instrument separation project, using Machine Learning.

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Oh, you scrolled down

Here are some of the recent projects I was in:

Below is the picture of the MVTX (MAPS-based VerTeX tracker) on top of the Cordinate-Measuring Machine table. We achieved 20-micron accuracy over 50 cm during the assembly.

The top picture is the Printed Circuit Board (PCB) design of the power distribution board for the MVTX power and readout units.

The bottom picture is the PCB for cable testing. I designed a cable to power the MVTX and test it when the company mass produces it.

Electromagnetic calorimeter prototyping

The above picture shows a 3 X 3 PbWO4 crystal EM calorimeter. Each crystal is wrapped with a reflective sheet so that the scintillated photons can bounce around and be collected to a photomultiplier tube on the right side. The only thing that is supporting the structure is carbon fiber space frames at both ends of the crystals (in black). I calculated the calorimeter resolution with a Monte Carlo simulation, providing the optimal material budget for the space frame.

Calorimeter optical bleaching

With a heavy radiation dose, the crystal loses its optical transmittance, i.e. gets dark. I did the R&D for its curing methods. One of which is injecting blue light using optical fiber. It is called optical bleaching.

Realistic MC simulation geometry

Realistic experimental setup in the simulation for precise radiation dose measurement. Included here but not visible is a magnetic field to reduce the radiation background on the detector 

An example: radiation flux calculation

During R&D and construction, I checked background radiation distribution with different energy and spatial distributions for various types of radiation. This is one of many processes for validating the MC simulation setup. The plot is for the gamma radiation.