末包 文彦

1983: As a doctor course student, I joined VENUS e+e- colliding beam experiment at TRISTAN. I stayed at KEK as an entrusted student from Tokyo Inst. Tech. throughout my DC student period. I was involved in the central drift chamber (CDC) subgroup. I did many test experiments for CDC R&D. I designed a low power preamplifire for the CDC.  It annoyed me a lot by spontaneous oscillations while testing circuits and I learned about difficulty of analog electronics.

My ph.D thesis became the first physics publication from the VENUS group and it showed that the top quark was heavier than 24GeV. (Now the top quark mass is known to be 173GeV.  My thesis limit was a little bit smaller. )

1987: I obtained a job at KEK and joined KL --> mu + e rare decay search experiment. I was in charge of e/pi/mu particle identification system. It was surprising to me that the "rare" CP violating KL--> pi^+ +pi^- decay was the main backgorund for this measurement. 

Unfortunately, KL --> mu + e decay was not observed but KL --> mu^+ + mu^- branching ratio was measured with the best precision at that time.

1989: I moved to Tohoku Univ. and joined the SLD e+e- colliding beam experiment at SLAC to study Z0 boson. I stayed at SLAC  for about half of my time for about 6 years period. At SLAC, I was involved in the VXD3 and CRID sub-detector groups. For VXD3, I designed a cluster processor algorithm to pick up hit pixels with very high S/N. The algorism was  implemented in, then becoming popular, a XILINX FPGA. VXD3 can identify b, c-quarks using the vertex displacement and CRID can separate s-quark jets from u/d quark jets through leading K/pi particle separation. With these strong quark flavor ID capability and polarized beam, SLD could measure asymmetry of the fermion-Z0 couplings precisely and therefore, the weak mixing angle, Theta_W, precisely.
 I was also in charge of the accounting job of US/Japan cooperation fund while  staying at SLAC. I learned how to handle piles of receipts from this experience. I enjoyed the life of silicon valley, then growing rapidly as the world IT center. 

Around 1996, I returned to Tohoku Univ. and became a starting member of the KamLAND experiment. KamLAND measured the reactor antineutrinos coming from several nuclear reactors ~200 kilometers away and discoverd the reactor neutrinio oscillation. I was in charge of the R&D of 1kton liquid scintillator (LS), and LS container: 13m diameter transparent nylon-EVOH balloon, etc. etc.  The construction of the KamLAND detector finished in 2001. The detector is still now the largest homogeneous LS detector in the world.

 For me, it was a big jump from 10g vertex detector CCD to kilo tons of liquid scintillatior, from fine electronics to brute hydraulics to deal, from above-ground neat accelerator lab. to a deep underground humid lab. and, from physics of 91GeV Z0 particle to possibly milli-eV neutrinos. However, these pre-career allows me to think neutrino physics from wider perspective, that helped me to write a text book "Neutrino Oscillations", later in 2015.
 In 2002, KamLAND announced the observation of the reactor neutrino deficit and soon after, clean oscillation pattern. I received the first Koshiba prize with my two colleagues in 2004 for those achievements.
 The sensitivity of the KamLAND detector turned out to be good enough to detect the geo-neutrinos whose energy and flux are much smaller than the reactor neutrinos. KamLAND measured the geo-neutrinos for the first time in the world and the result was published in Nature in 2005 and the article became the cover picture of this issue. 

In 2015, the initial KamLAND group was awarded Breakthrough Prize.

 KamLAND showed that the neutrino oscillation parameters, Theta12 is not so small. It means there is possibility to measure leptonic CP violation by neutrino oscillations in the future, IF another neutrino mixing angle Theta13 is not so small, either. Then detecting finite Theta13 became next very important subject. I and theorists wrote a paper in 2003 which showed that reactor measurement of direct theta13 at a baseline ~1.5km, is effective to reduce the ambiguities of the future accelerator measurement of CP violation and therefore, important. Then we formed a reactor-Theta13 experiment, KASKA, which was supposed to use, then the world most powerful Kashiwazaki-Kariwa nuclear power station. However, unfortunately the KASKA was not supported in the end.
 In 2006, the KASKA group joined French reactor-Theta13 project, Double Chooz (DC). DC-Japan budget was approved by JSPS as the category of special promotion of Grant-in-Aid for scientific research. DC-Japan group took responsibility of the photomultipliers, light calibration and data acquisition monitor systems and analysis. The detector construction was complete in the end of 2010. In Nov. 2011, the DC group reported an indication of finite Theta13 for the first time using reactor neutrinos. In the fall of 2014, the construction of the DC near detector was complete. In 2019, the new Theta13 result obtained using near-far detectors were uploaded to arXive.
In these days the Theta13 measured by reactor neutrino experiments (DC, DayaBay, RENO) are used to enhance the sensitivity of CP violation measurements in accelerator experiments (T2K, Nova) as expected back to 16 years ago.

Together with the academic studies, I  performed R&D for the reactor operation monitor by neutrinos for the safeguard purpose. By monitoring the reactor neutrinos, in principle,  it is possible to monitor the plutonium breeding in the reactor fuel and to know extraction amount in fuel exhange. The reactor neutrino monitor was one of  candidates of the novel technology program of IAEA. I have visited the IAEA head quarter to attend meetings.  Unfortunatelly, all Japanese reactors stopped operation for long time after the 2011 Great East Japan Earthquarke and this R&D  was also stopped.

In July 2016, I was selected as a Blaise Pascal Chair, by the Government of the Île-de-France Region, for subject of "Promotion of Neutrino Science". From April 2017, till Aug. 2018, I stayed at APC Lab., Paris as BPC and performed many seminars, lectures, Double Chooz experiment, R&D of novel neutrino detector technology: LiquidO, and wrote a text book, "Quantum Oscillations". I also enjoyed the Paris life very much.

Now, I am involved in the sterile neutrino experiment; JSNS2 at the MLF beam line of the JPARC accelerator complex. This experiment directly tests the LSND result with much improved performances.

I have contributed measurements of Theta_W, Theta12, Dm12, Theta13 and am hoping to detect Theta14 and Dm41 next, by JSNS2 experiment.

Now, I am  trying to measure decay at rest nue +Pb --> e^- + n + Bi cross section by detecting final state electron and neutron at J-PARC MLF (DaRveX experiment). If this is successful, it becomes possible to use Pb for low energy nue target.  It can be applied to measure low energy nue oscillations and supernova nue detection. 

In 2010, we(3) translated an English text book to Japanese (素粒子・原子核物理学の基礎) and it was printed In May 2011 (just after the Great East Japan Earthquarke. I finshied final draft in aftershocks. ) from Kyoritsu publishing company.
In 2015, I wrote a book "Neutrino Oscillations: A practical guide to basics and applications" as Springer lecture notes in physics series. I am glad this book is being continuously sold well.
In 2017. we(4) wrote a Japanese book "現代素粒子物理 (Modern Particle Physics)" from Morikita publishing company.

In 2021.3, I and prof. Shirai wrote another Japanes book "ニュートリノ物理学 (Neutrino Physics)" from Asakura publishing company. 

In 2021.6,  I wrote "Quantum Oscillations" as Springer lecture notes in physics series. This is an outcome from my lectures made as Blaise Pascal Chair during 2017~2018 in Europe. 

I enjoy writing text books because I can learn a lot by doing so and I am interested in teaching intuitive physics.

I am retiring Tohoku Univ. in 2024 but I am hoping to continue the research and educational activities.