Profile
Self Introduction
My name is ISHINO Hirokazu.
My research has currently focused on the satellite project, LiteBIRD, for the measurement of the
cosmic microwave background polarization and the development of superconducting detectors.
I like to go around my house by walk or bicycle to see the scenery for all the seasons, giving me various discoveries.
I also like to eat. Okayama is good for fruits, fishes and every type of food.
Biography
Born in Tokyo (Oct., 1971)
Tokyo Institute of Technology: BS (Physics) (Mar., 1994)
University of Tokyo: MS, (Mar., 1996), Ph.D (Physics) (Mar., 1999)
JSPS Postdoctoral Fellow, High Energy Accelerator Research Organization (Apr., 1999 - Mar., 2000)
Assistant Professor, Department of Physics, Tokyo Institute of Technology (Apr., 2000 - Mar., 2008)
Associate Professor, Department of Physics, Okayama University (Apr., 2008 - Dec., 2016)
Professor, Department of Physics, Okayama University (Jan., 2017 - Present)
My Research History
1994-1999 Research on Solar Neutrinos at Super-Kamiokande
Super-Kaimokande was my first ever experiment I joined as a graduate student. I had read an article in a science magazine about this experiment with a huge pool of water underneath of a mountain in my undergrad days. When I was an undergrad, I was only focused on trying to learn physics presented in front of me. As I started to see a graduation in site within a year, I read this article. So I applied this experiment, only because it triggered my curiosity.Kamiokande is a detector for proton decay and neutrino. Especially famous is the 1987 detection of neutrinos coming from supernova explosion in the Large Magellanic Cloud (SN 1987A). People were suggenting anomalies existing in numbers of observed solar and atomopheric neutrinos. When I entered graduate program, they were digging a hole for the Super-Kamiokande project, that is 20 times larger than the Kamiokande detector. I spend all my mater course years in this hole, for the construction of the Super-Kamiokande detector. I find myself extremely lucky to be involved in launching such a large scale project.
April of 1996 was the beginning of the Super-Kamiokande experiment. My research was mainly on solar neutrinos. Inside of the sun, nuclear fusion reacions occure frequently converting hydrogen nuclei to helium nuclei, and the energy released then is what makes the sun shine and us live on the earth. Neutrinos are created in this nuclear fusion process. We can calculate the number of these nutrinos arriving on earth from the relationship of the solar energy and the energy released by creating one helium atom, but we only observe half of the expected. Where did they go? Wrong calculations? This is the solar neutrino problem that puzzled us for 50 years since its discovery. At the time, there was a strong argument that the loss of solar neutrinos might be due to neutrino oscillations. Proving that was the mission of Super-Kamiokande, and to do that, we had to meaure the energy with an accuracy of 1 %. For that purpose we installed a linear electron accelerator so that we could inject electron beams into the detector to perform energy calibration. I also developed a novel method to measure the water transparency at high accuracy by means of electron events that occure from decaying cosmic-ray muons. Then the energy measurement accuracy was achieved. I was not able to obtaine a solid evidence of neutrino oscillation as a result of the measurement. However, I wrote my dissertation on the first observatin of solar neutrino spectrum in the world. My work was also published on Phys. Rev. Lett.. Later in 2001, combined analysis of SNO and Sper-Kamiokande proved that the mystery of solar neutrino dissaperance was due to neutrino osillations.
1999-2008 K2K Experiment
On the other hand, in 1998 Super-Kamiokande discovered that neutrinos do oscillate
and they are not massless from atommospheric neutrino observations.
To prove that, a new long baseline neutrino oscillation project was being planned.
The experiment is named K2K and it was to shoot man-made neutrino beams from KEK to Super-Kamiokande.
With a newly obtained PhD, I joined the K2K collaboration.
It was necessary that the neutrino flux imediatly after the beam generation was measured at 10 % accuracy.
I established a method to achieve that using the front-end detectors on the KEK site.
The K2K experiment was proceeding smoothly and the neutrino events at Super-Kamiokande had begun to accumulate.
At the time I was a post-doctoral JSPS fellow and I needed to think about my next job.
I appplied for a job opening at Tokyo Tech., and I was accepted as an assistant professor.
The position was not for K2K, but I was fortunate to be able to participate in the B-factory experiment.
2000-2008 B-factory (Belle) Experiment
The B-factory experiment at KEK started in 1999, the same year K2K started.
The main purpose of the B-factory experiment (Belle) was to measure violation of the CP symmetry between matter and antimatter
by creating many B mesons by colliding electrons and positrons and analysing their decaying processes.
I joined Belle in 2000. Until then my world was neutrino only and Belle project was completely new to me.
My first job at Belle was to maintain the existing Silicon Vertex Detector (SVD) and develop an upgraded version of SVD.
SVD exists at the innermost layer of the Belle detector and it is a device
that measures the position of the B meson decay at high accuracy. It is indespensible for the measurement of CP violation.
Due to its position, SVD receives high radiation originating from electron and positron beams,
so its performance is easily changed.
So I created a web monitor to check the SVD performance, organized SVD monitoring shifts
so that SVD collaborators all-over the world could take turns to check the detecotor operation every day.
I also participated in the SVD upgrade task.
SVD consists of layers of double-sided silicon detectors (DSSD) and DSSDs were manufactured by Hamamatsu Photonics.
I with colloborators and students assembled the DSSDs and build a SVD detector.
Our team also developed a new data readout system.
Belle recieved increasing beam intensities each year, and trigger frequency increased accordingly.
It was necessary that we had to acquire SVD data at 1 kHz or more.
I lead a team consisting of KEK stuff members and students to face this task.
We developed a system of DAQ with 12 PCs, cutting edge at the time, parallel-reading the data,
marging by an event-builder and sending the marged event data to the Belle offline system.
It was a difficult task, but at the end it was possible to achieve DAQ at 1.3 kHz.
Furthermore, we improved the SVD software. The accuracy of the SVD assembly was 100 microns at most, but 10 microns was required.
The difference had to be corrected by software, and we called it alignment.
There was a method of alignment developed previously, but it was not applicable for this versino of SVD.
We have established a new method after trial-and-error period of about 6 months to a year with students.
Performance evaluation using cosmic-ray muons resulted in a position resolution that is at least 20% better than the previous SVD.
I had an intense feeling of fulfillment, when the new SVD was installed at the time of the accelerator shutdown in the summer of 2003.
After the SVD development, I started to focus on physics analysis of Belle data.
CP violation was already discovered in the J/psi -> Ks channel at the time,
and one of the CKM mixing angles φ１was starting to be measured at high accuracy.
I was tasked to measure another mixing angle φ2.
As a φ2 team learder, I analyzed B->π＋πー data and oversaw the other analyses.
In my B->π＋πー analysis, I established a new method including particle ID information and
this increased the sensitivity to its limit. This led to the discovery of direct CP violation at 5σ in Aug., 2006.
The result was published in the Phys. Rev. Lett. article
and I recieved an Editor's Suggention as the highlight of the issue.
Our rival team in the US, BaBar, did a similar analysis at the time, but our results were incinsistent almost at 3σ.
There were much discussions then. However, in 2013 results our results moved closer and they became consistent.
2008-Now：LiteBIRD, Development of Superconducting Detectors, Supernova Detection
As I was moving from Tokyo Tech to Okayama University, I decided to aim for a new experiment.
I joined LiteBIRD, a satelite CMB ploarization measurement experiment,
proposed by Prof. Masashi HAZUMI of KEK, and started to work on the development of superconducting detectors.
I didn't know the details of superconductivity.
To develop a superconductin detector, the detector must be in a superconducting state.
That means we need to have a refrigerator that can cool down to extremely low temperatures.
Around 2007, we started work on it. At first, we learned its manufacturing techniques and performance evaluation methods at RIKEN.
Around the same time, the Superconductivity Detector (SCD) development group was launched
in the KEK Measuring Instruments Development Office.
I joined the group and proceeded with development as a team member.
We launched refrigerator systems at Okayama University and at KEK, and we fabricate superconducting detectors in the KEK clean room.
We aim to apply this superconducting detector as a completely new detector for the search for light dark matter,
and the students in my lab are working on device fabrications and their readout system development.
The scientific satellite LiteBIRD aims to accurately measure the polarization of cosmic microwave background radiation,
the oldest light in the universe, and approach the mystery of the inflation of the universe, which occurred before the Big Bang.
In 2008, I returned to Super-Kamiokande and began researching and developing supernova explosion monitors.
I developed a mechanism to detect a supernova explosion, an explosion that occures without a warning, with its neutrino detection,
calculate the direction at once and announce it to the world.
For more information about these studies, here