VATLY VATLY means “physics” in Vietnamese and is the acronym for Vietnam Auger Training LaboratorY 1. The Pierre Auger Observatory 2. Laboratory installations 3. The Vietnamese context 4. Publications

The Pierre Auger Observatory is located in the Argentinean pampas, at the antipode of Hanoi, and is dedicated to the study of extreme energy cosmic rays: Where do they come from? How are they accelerated? Which kind of particles are they? The low rate (~1/km 2 /century) requires a huge detector but the large size of the secondary particle showers (several billions over a few square kilometers) allow for a tiny sampling fraction: 1600 detectors, 10 m 2 each, 1.5 km apart on a 3000 km 2 area.

A developing shower

In addition to its array of ground Cherenkov counters, the Observatory includes 24 fluorescence eyes grouped in four stations. Data are transmitted by radio and dispatched to all laboratories in the Collaboration UV-Filter nm camera 440 PMTs 11 m 2 mirror

The Observatory has already obtained two important results, a guarantee for a long and rich future: -It has given evidence for photoproduction of pions on the cosmic microwave background, inducing the so-called GZK cut-off. -It has given evidence for a strong correlation between extreme energies cosmic rays and nearby galaxies, particularly galaxies hosting an active galactic nucleus.

VATLY analyses Pierre Auger data. The challenge is to find scientifically interesting topics, yet at the level of our abilities (the danger for developing countries being to serve as cheap labour). We have been successful at finding such topics. Two PhD students are performing detailed studies of the ground detector signals in order to determine the nature of the primary cosmic rays. They already contributed important and original results. A third PhD student measures detailed properties of the photomultiplier tubes used in the ground detector using a test bench he built in Hanoi, again making essential contributions. All three PhD theses are in cotutelle (joint supervision) with French universities (3 months in France, 9 in Hanoi), an excellent arrangement in all respects. Two of them have spent time on the site of the Observatory and helped with installation, maintenance and operation.

VATLY is equipped with detectors and electronics (obsolete but still working) which were given to us by colleagues when I first came to Hanoi, nine years ago. It gave us a chance to perform some interesting measurements (muon flux of particular interest to neutrino experiments such as SuperK and SNO as Hanoi sits on the world maximum of rigidity cut-off, 17 GeV). It also allowed for the construction of a replica of an Auger ground detector and satellite trigger counters allowing for the study of extensive air showers. This gave four master theses for VATLY students and is now keeping a PhD student busy. This way, the team is able to get familiarity and expertise with the Observatory hardware.

We are training students at bachelor, master and PhD levels in association with the National University of Sciences, the University of Education, the University of Technology and the Institute of Physics. We currently have four PhD students in the team. I have been giving lectures in the National University (astrophysics), University of education and Institute of physics (particle physics, superconductivity). We contribute actively to schools and conferences held in Vietnam.

We meet a number of essential difficulties related with the relatively low priority of fundamental research and university training in present days Vietnam. Wages of scientists, research or teaching, are insufficient (by a large factor) when compared with other social categories. Hence, second jobs, incompatible with a good quality university teaching and fundamental research. The system invites lack of rigor in the selection of students, teachers and scientific projects, not to mention corruption.

The level of Vietnamese universities in fundamental sciences is low. The backlog accumulated over thirty years of war and of difficult years of reconstruction has not been made up for. Deep changes are necessary to give Vietnam the university it deserves. Students prefer economic/financial to scientific careers and try hard to go study abroad where the better of them settle down. Brain drain is the worst of the diseases which Vietnam is enduring. Many families spend fortunes to send their kids study abroad. This money would be much better used to give the country universities fit for its dynamism and ambitions.

Fundamental research is not a priority of the country, which is natural in the present phase of its development. But few are conscious of the importance to spare a niche for it, be it with modest resources, in order to support applied research and train high level engineers and scientists having expertise with high technologies. The argument that «Vietnam is a poor country» is too often abusively invoked as an excuse for the absence of high level fundamental research. Few are aware of the many possibilities of high level research offered to a Vietnamese team of competent scientists by the international community.

Modern astrophysics, in spite of its spectacular progress over the past fifty years, is not taught in Vietnamese universities. Few professors are aware of recent advances and of how far it is from what astronomy was fifty years ago. The rigidity of the present university system makes its introduction difficult. We are trying to promote its teaching and to make its progress known, however with little success. We are also trying to promote research by explaining that while only a few privileged countries can afford to build giant telescopes and to launch satellites, all countries can take advantage of it and take part in the analysis of the data.

VATLY’s ambition is to train physicists of international stature motivated to promote in Vietnam good quality teaching and research of fundamental science. We enjoy unconditional support from the international community. Particularly invaluable is the support we get from the World Laboratory. In order to succeed, we need support and understanding from the Vietnamese government. Without it, our students will simply contribute more brain drain and join the diaspora.

PUBLICATIONS AND PRESENTATIONS AT CONFERENCES 1. Articles in relation with actions in favour of a better education: P. Darriulat, Tia Sang, 13( ) 16-19; Khoa hoc va to quoc, 15/16 (8-2007) 2-9; Tia Sang 18 ( ) 15-17; Viet Nam can cac truong dai hoc va vien nghien cuu tot hon, in Nhung van de giao duc hien nay quan diem & giai phap, Nha xuat ban tri thuc, Hanoi, 2007, ; Tia Sang, 8 ( ) 27-28, Etudes Vietnamiennes, 164 (2007) Graduation dissertations: P.T.T. Nhung, Dependence of the cosmic ray flux on atmospheric temperature, 2003, Hanoi National University. P.N. Diep, Dependence of the cosmic ray flux on atmospheric pressure, 2003, Hanoi National University. D.L.A. Huyen, Thoi gian song cua muon, 2004, Hanoi National University. N.V. Phuong, Un modèle simple du développement longitudinal des gerbes électromagnétiques, 2006, Hanoi National University. K.T. Phuong, The black hole in the centre of the Milky Way, 2006, Hanoi National University.

D.T. The, Optical properties of a Cherenkov counter, 2007, Hanoi University of Education. L.T. Huong, Galaxy collisions as possible sources of ultrahigh energy cosmic rays, Master theses: N H. Duong, Nghien cuu bat doi xung thong luong muon tai Hanoi, 2003, Ho Chi Minh City National University. P.T.T. Nhung, Performance studies of water Cherenkov counters, 2006, Hanoi National University. P.N. Diep, Detection and study of UHECRs, 2006, Hanoi Institute of Physics. P.N. Dong, The Cherenkov counters of the VATLY laboratory, 2006, Hanoi University of Technology. N.T. Thao, The detection of extensive air showers in Hanoi, 2007, Hanoi National University. 4. PhD theses: D.Q. Thieu, Nghien cuu tuong tac muon trong he detector mo phong tram do mat dat cua du an Pierre Auger, 2007.

5. Articles in international journals: P.N. Dinh et al., Measurement of the Vertical Cosmic Muon Flux in a Region of Large Rigidity Cutoff, Nuclear Physics B 627 (2002) 29. P.N. Dinh et al., Measurement of the Zenith Angle Distribution of the Cosmic Muon Flux in Hanoi, Nuclear Physics B 661 (2003) 302. P.N. Diep et al., Measurement of the east-west asymmetry of the cosmic muon flux in Hanoi, Nuclear Physics B 678 (2004) 3. J. Abraham et al. (Auger Collaboration), Properties and performance of the prototype instrument of the Pierre Auger Observatory, Nuclear Instruments and Methods, A523 (2004) 50. J. Abraham et al. (Auger Collaboration), An upper limit to the photon fraction in cosmic rays above eV from the Pierre Auger Observatory, Astroparticle Physics 27 (2007) 155. J. Abraham et al. (Auger Collaboration), Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory, Astroparticle Physics 27 (2007) 244. J. Abraham et al. (Auger Collaboration), Correlation of the highest energy cosmic rays with nearby extra-galactic objects, Science 318 (2007) 938. J. Abraham et al. (Auger Collaboration), Upper limit on the cosmic ray photon flux above eV using the surface detector of the Pierre Auger Observatory, Astroparticle Physics 29 (2008) 243.

J. Abraham et al. (Auger Collaboration), Correlation of the highest energy cosmic rays with the positions of nearby active galactic nuclei, Astroparticle Physics 29 (2008) Articles in Comm. Phys. Vietnam P.N. Diep et al., Dependence of the cosmic muon flux on atmospheric pressure and temperature, Com. Phys. Vietnam 14 (2003) 57. P.N. Diep et al., Atmospheric muons in Hanoi, Com. Phys. Vietnam 15 (2004) 55. P.N. Diep et al., On the detection of ultra-high energy cosmic rays, Com. Phys. Vietnam, 16 (2006) 129. P.N. Diep et al., Extensive air showers in Hanoi, Com. Phys. Vietnam, 17 (2007) 198. P. Darriulat, Physical scales: some elementary considerations, Comm. Phys. Vietnam, to be published. 7. Presentations at conferences P.N. Dinh et al., Cosmic ray research in Hanoi: The Auger experiment and measurements made at home, ISPUN02, Halong Bay, 2003, Nuclear Physics A722 (2003) 439c. D.Q.Thieu et al., Atmospheric muons in Hanoi, Proc. Vth Rencontres du Vietnam, Hanoi, August 2004, page 225.

P.N.Diep et al., Atmospheric muons in Hanoi, Proc. IXth APPC Conference, Hanoi, October 2004, page 87. P. Darriulat et al., Extreme energy cosmic rays and the Universe, Proc. IXth APPC conference, Hanoi, October 2004, page 21. P. Darriulat, Einstein inheritage: Modern cosmology, Einstein's day celebration, Hanoi, November P.T.T. Nhung et al., Cosmic ray studies at VATLY, Proc. Osaka- Hanoi Forum, Frontiers of Basic Science, Osaka University Press, 2006, page 92. P.N. Diep et al., VATLY, a cosmic ray laboratory in Hanoi: a progress report, Proc.VIth Renc.Vietnam, Hanoi, August 2006, page 279. P. Darriulat and P.N. Diep, Hanoi à l’ écoute du cosmos, L'Espace, Hanoi, December P. Darriulat, Particle physics for tomorrow: LHC, Opening address of the high energy department of HNU, February P. Darriulat, Black holes: recent advances, Annual Conference of the Vietnamese Physical Society (Theoretical physics), Da Nang, August, VATLY Newsletters are available on our web site:

We wish to express our deepest gratitude to the World Laboratory for its invaluable support. We also thank all those who help us or have helped us, both in Vietnam and abroad, in particular the members of the Auger collaboration, including the groups Orsay/LAL, Orsay/IPN and LPNHE/Jussieu with which we have cotutelle agreements, the Vietnamese Atomic Energy Commission and Ministry of Sciences and Technology, the French CNRS, the Rencontres du Vietnam, the Odon Vallet and Evariste Galois fellowships, the University of Catania, the Asialink EC programme, the RIKEN Laboratory.