WEB based user's applications for NA61/SHINE experiment at CERN

1. Introduction The Master Thesis titled „Web based users applications for NA61/SHINE experiment at CERN” presents the World Wide Web technologies that has been used during development of the software suite for NA61/SHINE experiment. Presented software was implemented and is use by a group of approximately sixty users 1 . The NA61/SHINE is one of many projects that takes place in the European Organization for Nuclear Research – CERN located near Geneva. 1.1. About CERN CERN (French: Organisation européenne pour la recherche nucléaire 2 ) was established on 29 th of September 1954. Poland is a member state since 1991, however a for a long time before joining CERN Poland as the only country of Communist Block had an observatory status. Nowadays Polish scientists are taking a part in a main CERN's experiments such as ALICE, ATLAS or CMS. CERN's essential scientific facilities are the particle physics accelerators and detectors. The beam provided by the accelerator or collider by interacting with a target or another particle beam triggers the production of a new particles. These particles – so called products of a collisions are registered by detectors, the detecting system consists of a set of different purposes detectors, such a system provides a very valuable scientific data. The largest and the most powerful CERN's and world's accelerator is LHC – Large Hadron Collider, the circumference of this incredibly complex machine equals 27 km. The LHC beam feeds the main experiments such as ALICE, ATLAS or CMS. The NA61/SHINE works with a beam from SPS which is a much smaller accelerator with a circumference of 6,9 km, SPS provides the beam to LHC. 1.2. NA61/SHINE Experiment The NA61/SHINE is one of the smallest CERN's experiments, however despite it's size the scien- tific contribution is definitely significant. In total in project 27 institutes takes a part, among them seven are Polish. About 200 persons from fifteen different countries contributes to the experiment. The abbreviation NA61 denotes „North Area 61” what indicates experiment number 61 located in the CERN's North Area. SHINE stands for “ S PS Heavy Ion and Neutrino Experiment ” what points out the purpose of the experiment which is to investigate heavy ions and neutrinos using SPS beam. The main aim of the experiment is to find critical point of strongly interacting matter. In a simple way the critical point can be described as an energy level at which the strong interactions that binds the structure of atom's nuclei are severed, thereafter the matter changes to so called quark-gluon plasma state. In SHINE the quark-gluon plasma is produced by colliding a particles previously accelerated with a target. For example the possible collisions are the collisions of a lead ions with a lead target, this kind of interactions is shortly called PbPb. The experiment's aim can be illustrated by an analogy to phase diagram of water, where the different phases depends on the temperature and pressure. The NA61/SHINE experiment aims to provide data that will allow physicists to de- velop an analogical chart for the matter. 1 number of active users in year 2011 2 the abbreviation CERN stands for French: Conseil Européen pour la Recherche Nucléaire, this name was in use for a short time period until this organization officially came into being in 1954, despite changing the name the old abbreviation was preserved 2 / 5 The products of collisions are registered by a set of sub-detectors, the data collected in this way allows on reconstruction of particle's tracks and particle identification. The NA61 detector is about 4 meters high and 13 meters length, comparing to another CERN's detectors the NA61 is relatively small. It's worth to mention that SHINE cooperates with T2K – Tokai to Kamioka experiment that is hosted by JPARC – Japan Proton Accelerator Research Complex. The NA61/SHINE detector data will help to develop better model for describing the production of pion and kaon particles in colli- sions of protons with a carbon target. This model is an essential for understanding the data from T2K. 1.3. NA61/SHINE work organization One of the terms typical for partial physics experiments is „Run”. It is the time period when the par- ticle physics detector collects data or is under calibration in order to achieve the best measurements results. Typically during the year, two runs are performed. The first one is called a „test run” which usually takes place during the spring time. This run lasts for about a week or two, it's goal is to test and cali- brate hardware and software before a the second one – the „physics run”. The physics run usually starts a few weeks later and lasts much longer, in general it takes about a few months. This run is in- tended for a data collecting. During the run time the detector must be continuously monitored. This necessity obligates NA61 collaborating institutes to designate members to stay in the experimental area in order to watch and keep a detector running. The time period when a member is obligated to stay is called a shift, the person that is working during this time is a shifter. 1.4. CERN and Information Technologies The Particle Physics and the Computer Science share the common areas. For instance, the need of collecting a terra bytes of data within a strict time constraints as well as performing later data analysis are a very interesting and challenging fields of the Computer Science. Very important contribution of CERN to IT world is World Wide Web (WWW or Web). Released in 1991 within a short time the system gained in a popularity, since it's creation it went through a long evolution adopting a new functionalities . N owadays Web 's applications are so wide that WWW is often mistakenly confused with the term „internet”. Currently, CERN develops a GRID system which in contrast to WWW that was created to share an information, provides the capabilities for sharing storage and computing power. 3 / 5 2. Aims and requirements of my master thesis In NA61/SHINE experiment where many institutes from around the word are involved, the need to organize the work in an efficient way led to develop a set of dedicated software applications. The requirement of easy access over the internet determined the choice of WWW technology as un- rivalled. An important features that draw the software development were: • scalability – it's a ability to maintain constant application performance regardless of amount of data stored by the system. It's desire because the system will be collecting data over a years. • flexibility – an application featured by this property is easy to be adopted to the new requirements. The software that is intended to support a work of a big and a dynamic group should be prepared for an unexpected changes. • security – means to protect the data against unauthorised access. This factor is very impor- tant as the applications are accessible directly from the internet. As a part of my master thesis I developed the applications to support administrative tasks as well as scientific data analysis. The first application is the ShiftsScheduler which helps to schedule the shifts for an upcoming runs, the next one - ElogLooker is an application to support data analysis. 2.1. ShiftsScheduler – shifts planning Most of scientists involved in experiment on everyday basis doesn't works at CERN but in theirs home institutes. For the run time the institutes delegates employees involved in NA61 to perform necessary work at the CERN side. During the run time the detector must be continuously watched, in addition – according to security rules at least two persons must be present at detector area. It's advised to have one experienced and one non-experienced person, so the knowledge can be transferred. Necessity of a shifts planning in an efficient way created a space for a shifts scheduling software. The Shifts Scheduler application implements mentioned requirements, but as well brings a series of an additional features such as run statistics or a contact book. 2.2. ElogLooker – Elog's data analysis During the run time so called „ run logbook” is maintained where detector parameters supplemented by optional comments can be noted. In the past the standard paper notebook was used, however NA61 waived usage of a paper in the favour of electronic record. The software chose by the collaboration for logbook keeping is devel- oped at Swiss Paul Scherrer Institut program „ Elog”. The web based application called „ ElogLooker” developed as a part of my master thesis extends the Elog by a data statistics presentation functionality. 4 / 5 3. Conclusion CERN is a very unique place, one of the very special thinks about this organization is the need to cooperate with a many institutes distributed all over the world. Need for such a cooperation led for inventing the WWW system which significantly improved the information exchange in a particle physicists circle s. Nowadays, WWW after a 20 years of development is not only the system for simple data sharing, but it's an advanced set of technologies that allows on building complex network applications. These applications, as requires only the web browser for running can be easily used independently from the operating system and a physical place. The basic requirement of my thesis was to develop a set of applications to improve the work of dis- tributed NA61/SHINE collaboration, the fact that there was no any doubts to choose the WWW technology proves that the World Wide Web is a great CERN's success story.