The Roland Maze Project

Roland Maze was a co-discoverer of Extensive Air Showers of cosmic rays. The array built by him on the roof of Ecole Normale Superieure in Paris enabled the observation of simultaneous registrations of high energy particles in two detectors separated by ~30 m. His name has been placed together with the name of Pierre Auger in the headers of the first papers of 1938 reporting about the discovery.
At the beginning of the fifties, when the cosmic ray laboratory in Lodz was being formed, Roland Maze closely collaborated with Polish physicists. It is not easy to estimate nowadays his role in creation of the Lodz group and its first scientific achievements. He was together with Aleksander Zawadzki, Juliusz Hibner, Jerzy Gawin and Jerzy Wdowczyk (among others) the co-author of many papers, which established the position of Lodz among distinguished centres of high energy physics in the world.
Comparing the scale and goals of presented further project with those of the international and over 100 mln $ Auger Project, it seems justified to call our enterprise with the name of Roland Maze, as a tribute to this great scientist.

Roland Maze in Lodz (1968)




Cosmic ray energy spectrum.
Physical background

The phenomenon of cosmic radiation is known for 90 years. It was discovered (as a Hoehenstrahlung) by Viktor Hess and now we knew that the Earth is constantly bombarded by the high energy particles coming from the outer space. Cosmic ray studies are recently intensively developed, especially in the region of the upper limit of energy spectrum (see Figure beside), where several single cases of particles with energies exceeding 1020eV (~50 J) have been observed. Such energies are 100 mln times higher than those which can be studied in laboratory experiments and most probably higher than those that can ever be achieved in experiments built by human hand. Apart from the obvious, but extremely compound problem what is going on with matter during collisions with such enormous energy release, the question what astrophysical mechanisms are at all able to produce particles with such energies is also very intriguing. If we add to this that the nature of these particles is also unknown (they can be protons, compound atomic nuclei, gamma quanta, neutrinos or even yet undiscovered new particles predicted by theories beyond the so called Standard Model), it can not be surprising, that to find answers to at least some of these questions just now large ground level arrays are being built (Auger Observatory) and quantitatively completely new satellite experiments (OWL, Air Watch, EUSO ) of budgets reaching hundreds mln $ are being planned.

Arrival directions of most energetic cosmic ray events.
Important technical problems

The main difficulty is due to the fact that the flux of particles with energies above 1020eV is of the order of 1 particle per square km per century (or even lower), so the detector area has to be sufficiently large to obtain required result in reasonable time. The biggest actually working experiment AGASA consists of particle counters spread over an area of 100km2. During ~20 years of work it has registered 17 such events (as has been claimed at the last cosmic ray conference in Hamburg in August this year, but there are opinions that this number can be overestimated). In the projected Auger experiment 1600 detectors will be spread over 10 times bigger area. The main goal of such experiments is to determine (or rather estimate) in each registered event the energy of the particle which has initiated in the atmosphere a phenomenon called an extensive air shower, i.e. the cascade of particles (mainly photons, electrons and muons) with lateral size at the observation level measured in kilometers. Such estimation is performed basing on measurement of particle density in a shower in a few points separated by several hundreds meters (1.5 km in the Auger experiment). Moreover, measuring the times of shower arrival to different detection points one can determine the direction on the celestial sphere from which the primary particle has come.
The single detector is essentially a very simple device. It usually consists of a few scintillation (or Cherenkov) counters connected to the electronic system with a simple coincidence trigger and converters of time and amplitude of signals to digital codes. The essence of large area experiments is a method of synchronization and communication between detectors and a system of collecting and storing the data. This can be performed by normal optical fibers, like in the AGASA experiment, or by radio, like in the Yakutsk array or in the Auger experiment. A non-trivial problem is also maintaining stable and reliable performance of the system (service) and providing power supply to the detectors separated in total by tens of kilometers.
Concept of the Maze project

In the proposed experiment detection points would be placed in the buildings (or better on the roofs) of Lodz high schools. Their net is dense enough (see Figure beside) to enable observation of particles starting from energies of 1018eV, for which expected frequency of interesting registrations is much greater (several thousands times) than for cases from the narrow region above 1020eV. So one can expect first interesting experimental results already in the preliminary stage of realisation of the project with a small number of detection points. While the large experiments are dedicated exclusively to big science, in our project each station (school) would constitute autonomous air shower array. Small, but developed enough to provide results which could themselves serve as material to interesting studies related to cosmic ray physics and to independent developing of data analysis methods.
For available spacing between detectors in a station (of the order of ~10 m) the chance of observing highest energy showers in one separate station is very small, but a special trigger system may provide full efficiency of registration of showers with energies ~ 1015eV falling on the detection area (100 m2). For a specific realisation (discrimination levels) one can obtain sensible frequency of events counted in 1 min-1.
To enable independent observations in a separate station (high school) each of them should be equipped with 4 scintillation counters of area ~ 1 m2. The electronic system should enable measurement of relative times with accuracy of ~ 5 ns (that would give angular resolution of ~ 5o) and measurement of signal amplitudes from all the detectors.
The system of converters and master elaboration would be connected to a PC-class computer, on which preliminary data analysis and storing would be performed. The scheme of a single detection station is shown in the figure.
To enable coordination of work of all the stations, which is the essence of described project, the GPS system seems at the moment the best for time synchronization. In the standard version GPS provides absolute time with sufficient accuracy (~300 ns) to synchronize events in different station. It seems reasonable to increase accuracy to several nanoseconds to enable additional determination of particle direction in cases of simultaneous registrations in several stations, that are expected for the highest energy showers, studies of which are the main scientific goal of this project.
Communication between stations would be realised via Internet (see the figure to the right). Permanent connection to the net is not demanded, as the data stored in computer memory can be only once per some time sent to the central server. The server would put the data in some order, store and archivise them, and make accessible for each group on demand. In this way each group taking part in the realisation of the project would be able to independently analyse the whole gathered data and perform its own original studies.
Map of high schools in the Lodz region.


The schematic view of the single Maze Project station.


The idea of the Maze Project network.
Realisation of the project

The first stage of project realisation would be devoted to detailed design of detectors and the basic software for the station. In parallel, a series of lectures in high schools will be organized to introduce students and teachers into the area of high energy physics, astrophysics and cosmic ray physics, and also to demonstrate assumptions and capabilities of the Maze project. In course of works on prototype stations and software the seminars devoted to particular solutions would be organized for teachers and students.
In the initial phase 2-4 prototype stations would be built and successively started. After several months of work (counting also necessary tests) the system should be sufficient to confirm the realised concept by showing physical registrations of very high energy showers, and correct and stable work of the whole system.

In the proposed version of the Maze project the detection stations would be separated by distance from half to two kilometers. Larger separation would cause that a station would never (?) in practice register an event in coincidence with any other, so it could realise only self-sufficient tasks, severely narrowing the sense of the whole enterprise. However, it is possible to formulate a serious research problem (from cosmic ray physics area) also for distant detection points. Quite recently reports about simultaneous registrations of extensive air showers in arrays separated by even hundreds of kilometers have appeared in the world literature. The idea explaining such phenomenon has been put forward by Gerasimova and Zatsepin already a long time ago. It assumes that the showers have been initiated by the fragments of atomic nucleus produced far above the Earth atmosphere, which managed to separate by such a great distance. Experimental studies are being carried actually to deny or confirm earlier reports.
It is evident that there are no principal obstacles to enlarge the activity in the frame of the Maze project outside the borders of Lodz and organize constructing of the detection nets (a few interested schools in one town would be sufficient) at big distances and analysing the data gathered by them from specific point of view. Every, not very small town is able (depending on resources and capabilities) to join the project.
Borders of our country are certainly not the borders for physics, and especially for cosmic ray physics. We may expect that similar projects will start also in other countries, for sure at first in US. The exchange of information, concepts, results and achievements via WWW would be undoubtedly valuable. It is not excluded, that the global network for observation of Gerasimova-Zatsepin effect could bring very interesting physical results.
Educational impact

The problem of finding young people who could eventually decide to devote themselves to science, and to physics in particular, is not a specific Polish problem, although it can relate to us in greater extent than to societies a bit more technologically developed. In whole Europe the diminishing interest in physics and in studying physics can be observed. The reasons are plural and this is not a place for analysing them.
It seems that introducing teachers of physics and students to the realisation of the project being in itself the physical project sensu stricte (and even more, making them direct performers of such a project), with the use of newest technologies, not only may, but for sure will cause an increase of interest, about which we wrote above.
Contact with centres where physics is done every day may reveal to the young people quite unknown for them possible ways of arranging their own future. The work in group on tests in the phase of starting the array, and then on analysing "their own" data, constructing "their own" software, presenting results on "their own" WWW pages, will give those young people fantastic possibility to show themselves off intellectually and simultaneously to adjust themselves to the work in a team.
The detection system of a station allows to conduct quite independent observations and studies for each group participating in the project. One can study for example:
  • de-coherence curve (i.e. to repeat the historical experiment of Maze)

  • temperature effect

  • barometric effect

  • angular distributions (zenithal and azimuthal) in order to find effective acceptance of the station array

  • anisotropy in celestial coordinates (and also Galactic coordinates)

  • shape of energy spectrum around 1015eV

  • correlations with activity of the Sun, the state of atmosphere, etc.

There are quite a few possibilities and the field for showing off for everybody is huge. Permanent contact ("on demand") with researchers should additionally broaden these possibilities.
In course of project development, beside communication via Internet, it seems important to organize gatherings and meetings of its participants: students, teachers and researchers. During such meetings, apart from the obvious exchange of information, sessions (seminars) should be organized, at which schools would present their achievements. The sessions could be accompanied by the lectures on physical topics more or less closely related to the Maze project. Because during the last International Cosmic Ray Conferences projects of similar systems have been presented in the form of short communications, it is very important to present also the Maze project to the society of physicists in a similar way at the next Conference, as soon as the project enters the stage of realisation. The results of works conducted in the frame of the Maze project after sufficiently long period of data acquisition would for sure fulfill the criteria demanded from scientific works published in refereed professional literature.
Other similar projects

  • ALTA (Large Area Time Coincidence Array) - University of Alberta, Canada. Each station will have scintillation counters set in a triangle on a roof of a school. %Because schools in this region are rather sparsely dispersed, The distance between the stations will be of the order of 10 km, so the array will be dedicated exclusively to looking for Gerasimova-Zatsepin effect.

  • WALTA - University of Washington, Seattle. In the Seattle area each station will be equipped with three 1 m2 scintillation counters. Up to the year 2002 installing of 10 - 20 detection points is planned.

  • CHICOS - Caltech, California State Univ., Univ. of California w Irvine. The project assumes %taking over used detectors from the old experiment in New Mexico (closing just now) and placing detectors in schools in the Los Angeles area during three years period (up to 2003). First 9 stations are being arranged actually. Plans assume that 10000 students and 300 teachers will be involved.% in the works !

  • CROP - University of Nebraska. In the first stage of realisation four stations will be started in the Lincoln/Omaha area. The project will engage 30 schools. equipped with 1 m2 scintillation detectors.

  • SCROD - Northeastern University, Boston.Avalanche photodiodes are planned to be used for registration of light from scintillators. The prototype of single detector has been designed and successfully tested.
Cosmic ray studies in Lodz

From over forty years experimental studies of extensive air showers have been performed in Lodz. At the beginning the technology of production of glass Geiger-Mueller tubes with outer cathode has been elaborated here. The first small air shower array has been built of such counters. The results obtained on this array allowed the Lodz centre, led then by Aleksander Zawadzki, to achieve an important place among the leading groups studying the passage of high energy particles through the atmosphere. The Lodz array has been then systematically developed and it was always fit both technologically and conceptually to the highest world standards. In the course of time the registration technique of large area scintillation counters and Conversi counters giving very precise measurement of particle densities has been introduced. Later the array was enriched with two detectors of the muon component of the showers: the ground-level hodoscope covered by a half meter layer of lead and the underground hodoscope placed at the depth of 15 m. In order to increase the range of distances in studied particle distributions an autonomous distant detection point with its own trigger and time registration system has been added. From the point of view of the Maze project, the Lodz array of those times resembled the system of two detection points planned in the project. Obviously, the synchronization of the distant detection point could not be realised via GPS, which at those times did not exist at all. In the last important step of development the Lodz array has been equipped with a hadron detector based on technology of wide spacing spark chambers and semi-calorimetric measurement of hadron energy.
Actually the Lodz array undergoes subsequent deep modernization. Neutron counters and large area underground muon telescope, which is under construction, will be used not only for extensive air shower studies, but also for research in the area of Solar physics. It is worth noticing, that the Lodz air shower array has been continuously working for forty years and rich experiences gathered during whole this time make the team of physicists connected to this array fully prepared to coordinate and lead the works in frame of the Maze project.
Summary
To summarize only one (main scientific) aspect of the Maze project: the cosmic ray energy spectrum above 1018eV, we would like to point out that the collection area of the Maze experiment is comparable to the bigest existing air shower array AGASA. Some of our solutions (e.g., four independent detectors in each station) make our planned array even better, or at least different. Results on energy spectrum from our project are expected to be of similar quality like these of other experiments published nowadays in top physics journals and should enrich the still unsufficient statistic of ultra high energy cosmic ray events. Additionally, the access to raw data and measurement details gives an excelent opportunity to study important physical problems on much deeper level taht it is possible now with only partially published data from other groups like, e.g., AGASA. This opens the new wide area for theoretical interpretation of cosmic ray spectra and giant air shower properties.
The second important aspect for the Maze project is its educational impact which could be even more important than the scientific one.
The experience gathered for about forty years by the people in Lodz laboratory gives the perspectives that the project shortly described here could be successfully realised.

The Project as EU Integrated Project