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Liangjian Wen | IHEP | China

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Neutrinos are in a year of wonders

Sunday, September 25th, 2011

After the T2K’s indication of non-zero theta13, neutrinos from LNGS throw out another bomb: the neutrino speed > c. The non-zero theta13 might only attract the eyes of particle physicists, but ‘the neutrino speed > c’ is really an earthquake to the fundamentals of whole modern physics and causes worldwide discussions.

Most people regard the T2K’s non-zero theta13 result is an ‘indication’, not a ‘discovery’, because the significance is only 2.5 sigma. Though the significance from OPERA is 6 sigma (http://static.arxiv.org/pdf/1109.4897.pdf), they are very cautious about the anomaly they observed. Almost every number in their paper has been cross-checked independently. Perhaps the neutrinos have some other properties that we never thought before, otherwise some systematic effects are in the dark. After all, the accurate metrology techniques used by OPERA, like GPS and geodesy, are common and mature. We also use them in our Daya Bay experiment to synchronize different experimental sites and measure the reactor baseline, of cause, with relative low precision requirements. So it is very important that other experiment can repeat this measurement with different experimental systematics.

 Looking at OPERA’s results, I recall one thing. In this year’s ISSP11, students were asking Prof. Ting about when they will release the first results of AMS. He said it is not about time, it’s about right or wrong. “Likely the human will never send a detector like AMS into space again in next a few decades, so we have to tell people the right thing”, says Prof. Ting when ended his lecture.

 Now it seems neutrinos become in a year of wonders. What is the next? I would prefer zero theta13, ^_^.

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ISSP11 (I) — Forewords

Sunday, June 26th, 2011

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It is more than two months since my first blogging. There were several events that could be good topics for blogging, such as the Chinese traditional dragon boat festival, the launching of the AMS detector, the recent indication of a large theta13 by the T2K accelerator neutrino experiment, etc. However, I was fully occupied and even not have a chance to write one word. This is not so good as a blogger. I need write something down. Let me start with a recent interesting event—ISSP.

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When walking on the small path of Erice (a beautiful town in Sicily, Italy) and breathing the mixture atmosphere from Mediterranean and this old town, I believe I’m back to here again. This is my second time to be Erice to participate in the International School of Subnuclear Physics (ISSP). This year is the first of the three devoted to the celebrations of the 50th Anniversary of the Subnuclear Physics School. Why the celebration will be during three year? The school was first started in 1961 by Prof. Antonino Zichichi and John Bell at CERN and formally established in 1962 with Bell, Blackett, Weisskopf and Rabi in Geneva (CERN); the first Course at Erice being in June 1963. So they have three celebrations.

 ISSP is a high level school, under <ETTORE MAJORANA> Foundation and Centre for Scientific Culture (EMFCSC). Experimental physicists like to talk about numbers. Here are some about the EMFCSC activities since 1963:

123 schools, 1,497 courses, 103,484 participants (124 of which NOBEL Laureates) coming from 932 universities and laboratories of 140 nations

 ISSP is also very interesting. At the end of the School twenty-three Diplomas will be awarded to the Best New Talents by a Committee composed by the Lecturers and the Invited Scientists. Each Deploma is named after a late physicist, to stimulate the young talents. It is really like a ‘school’, rather than the summer school I’ve participated or heard.

It will be a great enjoyment to discuss physics with the  top physicists, S. Ting, A. Zichichi, G. ‘t Hooft, H. Fritzsch, P. Minkowski, M. J. Tannenbaum, etc.

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Nuclear Safety

Thursday, April 21st, 2011

Following former Quantum Diaries bloggers Zhizhong Xing and Jun Cao, I became the third person from IHEP (Institute of High Energy Physics, China) to blogging Quantum Diaries. I was quite happy, since it’s like a sign that I’m becoming a real physicist, ^_^. 

Last week we have our collaboration workshops at Daya Bay experimental site. The security check is more restrict than before due to the accident at Fukushima, where the world’s eyes are now focusing on. Right after the news about radioactive leakage, I received a few calls from friends, asking how serious it is and what is the influence. They thought I studies nuclear power related things, obviously they were cheated by my major’s name.

The accident causes international reactions. China has also suspended approval for new nuclear power stations following the accident at Fukushima Daiichi plant. It is not strange, because if there is an accident, it would be worse since many of the new proposed plants are near high-population areas. Our State Council states that the safety is our top priority in developing nuclear power plants. I’m happy with this.

Recently I get to know a concept, Safety Culture. Though in the Daya Bay experiment we follow a lot of safety requirements and procedures for onsite work, I never thought safety could be a culture. The concept originated after Chernobyl disaster. This concept was introduced to explain how the lack of knowledge and understanding of risk and safety by the employees and organization contribute to the outcome of the disaster. In near future, the nuclear power might be the most important power source since the coal will be exhausted soon. Nuclear safety indeed should be well known and be taken seriously by the whole society. There was a kind of joke. Last month,   shoppers have been buying up lots of salt in many parts of our country, partly believing that it could protect them against radiation, and partly thinking future salt could be contaminated by radiation leakage. It’s unbelievable some guy bought tons of salt.

Another issue is nuclear spent fuel. Currently deep burying is the only way to deal with it. This is risky. High precision reactor neutrino experiments like Daya Bay also don’t like it, and we need consider its contribution to the observed neutrino oscillation. ADS (Accelerator Driven Sub-critical System), is very promising to resolve the spent fuel issue. IHEP is starting the R&D of ADS project.

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