Badanie zderzeń proton-proton, hadron-jądro oraz jądro-jądro przy relatywistycznych energiach w ramach eksperymentu NA61/SHINE przy CERN SPS

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1 Tytuł: Badanie zderzeń proton-proton, hadron-jądro oraz jądro-jądro przy relatywistycznych energiach w ramach eksperymentu NA61/SHINE przy CERN SPS Study of proton-proton, hadron-nucleus and nucleus-nucleus relativistic collisions in the NA61/SHINE experiment at the CERN SPS C. Streszczenie projektu 1. Cel prowadzonych badań/hipoteza badawcza Celem projektu jest prowadzenie przez zespoły badawcze będące członkami konsorcjum HADRONY-NA61/SHINE badań zderzeń hadronów i jąder atomowych z jądrami w ramach eksperymentu NA61/SHINE realizowanego w CERN przy akceleratorze SPS. Badania prowadzone w ramach NA61/SHINE mają dwa naukowe cele: 1. poszukiwanie punktu krytycznego materii podlegającej oddziaływaniom silnym oraz badanie własności produkcji hadronów przy progu na uwolnienie partonów w oddziaływaniach relatywistycznych jonów; 2. uzyskanie precyzyjnych danych dotyczących zderzeń hadronów z jądrami atomowymi niezbędnych do modelowania procesów, w których produkowane są neutrina, oraz opisu oddziaływań promieni kosmicznych w atmosferze ziemskiej. 2. Zastosowana metoda badawcza/metodyka Ad. 1. Fakt powstawania plazmy kwarkowo-gluonowej przy energiach RHIC-u nie budzi poważnych wątpliwości, natomiast kwestią budzącą spory jest wielkość minimalnej energii zderzenia (energii progowej), przy której występuje produkcja plazmy. Istnieją poważne argumenty, że energia progowa w centrum masy wynosi zaledwie 8 GeV na parę zderzających się nukleonów (w układzie ze spoczywającą tarczą odpowiada to energii wiązki równej 30 GeV). Przy tej bowiem energii zaobserwowano w eksperymencie NA49 w zderzeniach najcięższych jąder atomowych nieregularności trzech fizycznych charakterystyk jako funkcji energii zderzenia: silne maksimum stosunku krotności K + do π + (horn), wypłaszczenie nachylenia rozkładu pędu poprzecznego K + (step) oraz zmianę nachylenia krotności hadronów ujemnych (kink). Zachodzi pytanie przy jakiej wielkości zderzanych jąder owe jakościowe zmiany występują. Szczegółowe przebadanie zaobserwowanych efektów, które mogą być spowodowane właśnie przekraczaniem progu na produkcję plazmy kwarkowo-gluonowej, oraz analiza innych charakterystyk zderzenia, w szczególności fluktuacji różnych wielkości, w zakresie energii zderzenia wokół 8 GeV w centrum masy przy oddziaływaniach lżejszych jąder jest głównym celem eksperymentu NA61/SHINE.

2 Nasz projekt szczegółowo te zamiary przedstawia. W porównaniu do NA49, eksperyment NA61/SHINE poszerzy listę badanych charakterystyk zderzających się jąder, szczególnie o wrażliwe na występowanie przejścia fazowego fluktuacje różnych wielkości fizycznych. Zamierzamy badać fluktuacje krotności produkowanych cząstek, ich pędu poprzecznego oraz składu chemicznego (zestawu produkowanych cząstek) końcowego stanu zderzenia. Program badania zderzeń jąder atomowych został zapoczątkowany w roku 2009 i będzie kontynuowany co najmniej do roku Ad. 2. Odkrycie zjawiska oscylacji neutrin było najważniejszym dokonaniem fizyki cząstek elementarnych ostatnich lat. Obecnie rozpoczynają swoją działalność eksperymenty nowej generacji (T2K, Nova, Icarus i inne), których celem jest precyzyjne określenie parametrów mieszania neutrin, w szczególności ich mas. Dokładność tych pomiarów zależy w decydujący sposób od znajomości intensywności pierwotnej wiązki neutrin, co z kolei wymaga precyzyjnego określenia procesów, w których neutrina są produkowane. Okazuje się, że dotychczas zebrane dane dotyczące produkcji pionów w zderzeniach protonów z lekkimi jądrami są daleko niewystarczające i z tego powodu jednym z celów eksperymentu. NA61/SHINE jest dostarczenie takich danych. Dla potrzeb eksperymentu T2K zostały już zebrane dane dotyczące produkcji pionów w zderzeniach p + C przy energii 30 GeV. Pomiary były prowadzone na cienkiej tarczy węglowej oraz z wykorzystaniem repliki tarczy stosowanej w eksperymencie T2K. Proponowane przez nas badania będą dotyczyły analizy i interpretacji uzyskanych rezultatów. 3. Wpływ spodziewanych rezultatów na rozwój nauki, cywilizacji, społeczeństwa Głównym celem eksperymentu NA61/SHINE jest otrzymanie fizycznych rezultatów, które pomogą posunąć naprzód wiedzę ludzkości dotyczącą podstawowych własności cząstek elementarnych, ich oddziaływań oraz własności Wszechświata jako całości. Ad. 1. Wyniki uzyskane w ramach programu badania zderzeń ciężkich jonów powinny bezpośrednio pozwolić na sprecyzowanie właściwości przejścia między dwoma fazami silnie oddziaływującej materii: gazem hadronowym i plazmą kwarkowo-gluonową. Ponadto prowadzone badania mogą pozwolić na odkrycie punktu krytycznego materii jądrowej. Frank Wilczek, laureat nagrody Nobla z roku 2004 wyraził następującą opinię o projekcie eksperymentu NA61/SHINE: według mnie należy podkreślić, że istnienie tego punktu krytycznego jest ważnym przewidywaniem [teorii -przyp. tłum.] QCD oraz że określenie jego lokalizacji dostarczy bardzo wartościowych wskazówek dla skonstruowania diagramu fazowego [silnie oddziaływującej materii -przyp. tłum.]. Poza tym, że rezultat jest sam w sobie interesujący, stymulowałby także badania w ramach teorii cechowania na sieciach oraz astrofizyki gwiazd neutronowych. Mam oczywiście świadomość, że jest wiele ważnych, czasami konkurujących ze sobą priorytetów wykorzystania cennych zasobów CERN-u, więc jest ważne aby motywacja każdego z projektów była jasna i znacząca wszystko do czego tutaj dążę to podkreślenie, że projekt NA49-future (teraz NA61/SHINE) spełnia wysokie standardy w ramach tych kryteriów. Ad. 2. Rezultaty uzyskane w ramach program neutrinowego eksperymentu NA61/SHINE pozwolą w sposób pośredni, jako precyzyjne dane referencyjne dla eksperymentu T2K przy J- PARC w Japonii, określić podstawowe własności neutrin, ich masy i kąty mieszania. Koichiro

3 Nishikawa, dyrektor Instytutu Badań Jądrowych i Cząstek Elementarnych KEK oraz zastępca dyrektora w centrum J-PARC w Japonii, napisał:... Pomiary produkcji pionów i kaonów, takie jak te zaproponowane z wykorzystaniem istniejącego detektora NA49 w CERN-ie (SPSC-I-235) (teraz NA61/SHINE) są bardzo ważne dla zrozumienia struktury wiązki neutrin w eksperymencie T2K i pozwolą na osiągnięcie zaplanowanych celów przez T2K. Rezultaty otrzymane przez eksperyment NA61/SHINE w aspekcie badań promieniowania kosmicznego pozwolą w sposób pośredni, jako referencja dla danych zebranych przez Obserwatorium Pierre Auger w Argentynie, na precyzyjne badanie strumienia i kompozycji promieniowania kosmicznego w zakresie bardzo wysokich energii (powyżej 10^19 ev), co pozwoli na wyjaśnienie jego miejsca pochodzenia w kosmosie. Przedstawiciele Pierre Auger Observatory, Giorgio Matthiae oraz Alan Watson, napisali: Ostatnio zaproponowany został eksperyment ze stacjonarną tarczą przy CERN SPS. Będzie on wykorzystywał istniejący układ eksperymentalny NA49 (teraz NA61/SHINE) do pomiarów, oprócz innych reakcji, oddziaływań protonów i pionów z jądrami węgla (patrz CERN-SPSC ). Poprzez ten list chcielibyśmy wyrazić wielkie zainteresowanie kolaboracji Pierre Auger dla pomiarów widm wtórnych pionów i kaonów przy tych kombinacjach pocisku i tarczy.... Istotnym jest, aby podkreślić, że NA61/SHINE jest wyjątkowym przykładem synergii pomiędzy trzema programami badań fizycznych. Pozwala to na otrzymanie wyników efektywnie i tanio. Rola i wkład polskich grup w NA61/SHINE są krytyczne. Dlatego przyszłość całego projektu zależy w decydujący sposób od zatwierdzenia grantu NCN, o który ubiegamy się w niniejszym wniosku. 4. Korzyści wynikające ze współpracy z partnerem zagranicznym, wartość dodana wynikająca ze współpracy międzynarodowej w języku polskim Wśród instytucji tworzących kolaborację NA61/SHINE jest siedem polskich placówek naukowych skupionych w ramach konsorcjum HADRONY-NA61/SHINE. Są to Narodowe Centrum Badań Jądrowych, Politechnika Warszawska, Uniwersytet Jagielloński, Uniwersytet Jana Kochanowskiego, Uniwersytet Śląski, Uniwersytet Warszawski i Uniwersytet Wrocławski. Wieloosobowe grupy z tych instytucji przyjęły na siebie poważne zobowiązania i odgrywają kluczową rolę w całym przedsięwzięciu. Jeśli uwzględnić, że pomysłodawcą, szefem i spiritus movens całego programu NA61/SHINE jest Marek Gaździcki, mamy tutaj do czynienia z unikalnym przypadkiem eksperymentu fizyki wysokich energii o dominującym polskim wkładzie. Prowadzone przez nas badania dostarczą bardzo interesujących danych dotyczących progu uwolnienia kwarków i pozwolą na odkrycie punktu krytycznego silnie oddziaływującej materii jeśli takowy istnieje. Rezultaty analiz odziaływania protonów z tarczą węglową będą miały istotny wpływ na sukces eksperymentu T2K. C. Summary of the project

4 1. Research goals/hypothesis The aim of the project is carrying out study of hadron and nucleus collisions with nuclei in the NA61/SHINE experiment, which is being conducted at the CERN SPS accelerator facility, by research teams being members of the HADRONY-NA61/SHINE consortium. The research in the NA61/SHINE has two scientific goals: 1. Search for the critical point of strongly interacting matter and study of properties of hadron production at the onset of deconfinement in relativistic ion collisions; 2. Precision measurements of hadron-nucleus collisions needed for modeling of processes in which neutrinos are produced and description of cosmic ray interactions in the atmosphere. 2. Research method applied/methodology Ad. 1. The fact that quark-gluon plasma is created at collision energies available at RHIC does not arouse serious doubts. However, a questionable issue is the minimum collision energy (threshold energy) at which plasma is being created. There are serious arguments in favour of a hypothesis that the threshold center of mass energy is as low as 8 GeV per colliding nucleon pair (it corresponds to the beam energy of 30 GeV in the frame of a stationary target). This is because at this energy in the NA49 experiment, in collisions of the heaviest nuclei, irregularities of three physical observables as functions of collision energy were observed: a strong maximum of the ratio of K + to π + multiplicities (horn), flattening of an inverse slope of transverse momentum distribution of K + (step) and a change of a slope of negatively charged hadrons multiplicity (kink). A question rises: at what size of colliding nuclei these qualitative changes appear? A precision study of observed effects, which are likely to be caused by traversing the threshold for the quark-gluon plasma production, and an analysis of other characteristics of a collision, especially fluctuations of various observables, in a range of energies around 8 GeV at the center of mass in interactions of light nuclei, is the main goal of the NA61/SHINE experiment. Our project describes these intentions in detail. In comparison to NA49, the NA61/SHINE experiment will broaden the list of studied characteristics of colliding nuclei, especially including fluctuations of various physical quantities which are sensitive to the phase transition. We plan to investigate fluctuations of multiplicities of produced particles, of their transverse momenta and of chemical composition of the final state of the collision. The ion collisions program was started in 2009 and will be continued until at least Ad. 2. The discovery of neutrino oscillations is the most important achievement of particle physics of recent years. Currently next generation experiments (T2K, Nova, Icarus and others) begin their activity. Their goal is to precisely determine parameters of neutrino mixing, especially neutrino masses. Accuracy of these measurements relies heavily on the knowledge of the primary neutrino beam intensity, what in turn requires precise characterization of processes in which neutrinos are produced. It turns out, that already available data on pion production in proton collisions with light nuclei are by far insufficient. This is why one of goals of the NA61/SHINE experiment is to provide such data. For the T2K experiment, data on pion

5 production in proton-carbon collisions at the beam energy of 30 GeV, were already collected. Measurements were conducted with a thin carbon target as well as with the replica of the T2K target. Study proposed by us concerns data analysis and interpretation of obtained results. 3. Expected impact of research results on progress of science, civilization and society The primary goal of NA61/SHINE is to obtain physics results which will significantly advance or help to advance human knowledge on basic properties of elementary particles and their interactions as well as properties of the universe. Ad. 1. The results obtained within the heavy ion program shall directly allow to uncover properties of the transition between two phases of strongly interacting matter: hadron gas and quark-gluon plasma. Moreover, they may allow for a discovery of the critical point of strongly interacting matter. Frank Wilczek, the Nobel prize winner in physics in 2004, supported the NA61/SHINE proposal as following: ''... I think it is appropriate to emphasize that the existence of this critical point is a major prediction of QCD, and that learning its location will give us very valuable guidance in formulating the phase diagram. Besides its intrinsic interest, the result would stimulate research both in lattice gauge theory and in neutron star astrophysics. I realize there are many important, sometimes conflicting priorities for using the valuable resources at CERN, of course, so it's important that the motivations for each proposal are clear and significant -- all I want to do here is to emphasize that the NA49-future (now NA61/SHINE) proposal meets high standards by those measures. '' Ad. 2. The results obtained within the NA61/SHINE neutrino program will indirectly, as precision reference data for the T2K experiment at J-PARC, Japan, allow to establish basic properties of neutrinos, their masses and mixing angles. Koichiro Nishikawa, Director of the Institute of Particle and Nuclear Studies KEK as well as the Deputy Director of J-PARC Center, Japan wrote: ''... The measurements of the production yields of pions and kaons such as the ones proposed with the existing NA49 detector at CERN (SPSC-I-235) (now NA61/SHINE) are of high importance to the understanding of the T2K neutrino beam and will allow T2K to reach its design goals....'' The results obtained within the NA61/SHINE cosmic-ray program will indirectly, as reference data for the Pierre Auger Observatory in Argentina, allow a precise investigation of flux and composition of ultra-high energy cosmic-rays (above ev) and thus etablish their origin in the Universe. The spokesperson of the Pierre Auger Observatory, Giorgio Matthiae and Alan Watson, wrote: ''... Recently a fixed target experiment has been proposed for the CERN SPS. This would make use of the existing NA49 detector set-up to measure proton and pion interactions with carbon nuclei (see CERN-SPSC ), (now NA61/SHINE) in addition to other reactions. Through this letter we would like to express the great interest of the Pierre Auger Collaboration in the measurement of secondary pion and kaon spectra with these projectile/target combinations....'' It is important to stress that NA61/SHINE is a unique example of the synergy between three different physics programs. This allows to obtain the results efficiently and at a low cost.

6 The role and contribution of the Polish groups to NA61/SHINE is crucial. Thus the future of the project heavily depends on the approval of the requested NCN grant. 4. Benefits of collaboration with the foreign partner, value added resulting from the international collaboration Among institutions participating in the NA61/SHINE Collaboration, there are seven polish scientific institutes that constitute the HADRONY-NA61/SHINE consortium. These are: National Nuclear Research Center, Warsaw University of Technology, Jagiellonian University, Jan Kochanowski University, University of Silesia, University of Warsaw and University of Wroclaw. Multimember groups from these institutions took on serious duties and play a key role in the whole project. If we take into consideration the fact, that the initiator, leader and spiritus movens of the NA61/SHINE experiment is Marek Gaździcki, we come across a unique case of an experiment in the field of high energy physics where polish contribution is the dominating one. Our research will provide an exceptional data fir the onset of deconfinement and will allow for a discovery of the critical point of the strongly interacting matter if it exists. Results of analysis of proton-carbon interactions will have a substantial impact on a success of the T2K experiment. C1. Uzasadnienie - badania podstawowe Prace prowadzone przez uczestników konsorcjum HADRONY-NA61/SHINE koncentrują się na badaniu podstawowych własności silnie odziaływującej materii oraz dostarczają danych do dla eksperymentu T2K badającego fundamentalny problem określenia masy neutrin. Obydwie tematyki proponowanych badań należą do klasy badań podstawowych. C1. Justification fundamental research The work conducted by members of the HADRONY-NA61/SHINE consortium, concentrates on a study of fundamental properties of the strongly interacting matter and provide data for the T2K experiment, which investigates fundamental problem of neutrino mass determination. Both topics mentioned above belong to the class of fundamental studies. ZAŁĄCZNIKI 1. Skrócony opis projektu w języku polskim Skrócony opis projektu badawczego nie może być identyczny ze streszczeniem projektu (maks. do 3 stron standardowego

7 maszynopisu, w tym cel naukowy projektu, znaczenie projektu oraz wymierny, udokumentowany efekt podjętego problemu, korzyści wynikające ze współpracy międzynarodowej) do zrobienia ZAŁĄCZNIKI W JĘZYKU ANGIELSKIM 1. Cel naukowy projektu (jaki problem wnioskodawca podejmuje się rozwiązać, co jest jego istotą, zakładane hipotezy badawcze, spodziewany efekt końcowy, maks. 100 słów) The group of Polish scientific institutions will pursue a rich physics program: First, the nuclear collisions will be studied extensively at SPS energies. The energy and system size scan will be performed with the aim of studying properties of the onset of deconfinement and searching for the critical point of strongly interacting matter. Second, analysis of the precise hadron production measurements for proton + carbon system will be performed to deliver input for the calculations of the neutrino flux in the T2K experiment and for more reliable simulations of cosmic ray air showers in the Pierre Auger and KASCADE experiments. 2. Znaczenie projektu (co uzasadnia podjęcie tego problemu, jakie przesłanki skłaniają wnioskodawcę do podjęcia proponowanego tematu, znaczenie wyników projektu dla rozwoju danej dziedziny i dyscypliny naukowej oraz rozwoju cywilizacyjnego, czy w przypadku pozytywnych wyników będą one mogły znaleźć praktyczne zastosowanie, maks. 300 słów) Ad 1. The quark model of hadron classification proposed by Murray Gell-Mann and George Zweig in 1964 motivated the opinion that a new state of matter, namely strongly interacting matter composed of subhadronic constituents, may exist. Soon thereafter, quantum chromodynamics (QCD) was formulated as the theory of strong interactions, with quarks and gluons as elementary constituents. As a natural consequence, the existence of a state of quasi-free quarks and gluons the QCD quark gluon plasma (QGP) was suggested by Edward Shuryak in Measurements from an array of experiments were surprisingly well described by statistical and hydrodynamical models. They indicated that the created system of strongly interacting particles is close to at least local equilibrium (Heinz and Jacob 2000). Thus, a

8 necessary condition for QGP creation in heavy-ion collisions was found to be fulfilled. The "only" remaining problem was the identification of unique experimental signatures of QGP. Ad. 2 At present the neutrino beams are generated by the conventional technique: a beam of tens GeV protons is directed at a target to produce a large number (10 12 or more) of hadrons, mainly pions with a small admixture of kaons. These are then focused in the direction desired for the neutrino beam and they decay producing neutrinos in a decay tunnel. In the absence of a good theory of hadronic interactions, a precise prediction of the properties of such neutrino beams requires measurements of particle production at an unprecedented level of precision. The role of the NA61/SHINE experiment at CERN SPS is to perform these hadron production measurements. These data have already proved important for the extraction of the first results on electron-neutrino appearance and muon-neutrino disappearance in T2K. 3. Istniejący stan wiedzy w zakresie tematu badań (jaki oryginalny wkład wniesie rozwiązanie postawionego problemu do dorobku danej dyscypliny naukowej w Polsce i na świecie, czy w Polsce i na świecie jest to problem nowy czy kontynuowany i w jakim zakresie weryfikuje utarte poglądy i dotychczasowy stan wiedzy)??? Ad 1. Precise quantitative predictions related to production of quark-gluon plasma are currently impossible to calculate within QCD and predictions of phenomenological models suffer from large uncertainties. Therefore, the results of the measurements were only suggestive of the production of QGP in heavy-ion collisions at the top SPS energy. The same situation persisted at the top energies of Brookhaven s Relativistic Heavy Ion Collider (RHIC) and seems to be repeated at the LHC. Despite many arguments in favour of the creation of QGP at these energies, its discovery cannot be claimed from these data alone. A different strategy for identifying the creation of QGP was followed by the NA49 experiment at the SPS and is now being continued by its successor NA61/SHINE, as well as by the STAR experiment at RHIC. The idea is to measure quantities that are sensitive to the state of strongly interacting matter as a function of collision energy in, for example, central lead lead collisions.

9 This strategy, and the corresponding NA49 energy-scan programme, were motivated in particular by a statistical model of the early stage of nucleus nucleus collisions (Gazdzicki and Gorenstein 1999). It predicted that the onset of deconfinement should lead to rapid changes of the collision-energy dependence of bulk properties of produced hadrons, all appearing in a common energy domain. Data from 1999 to 2002 on central Pb+Pb collisions at 20A, 30A, 40A, 80A and 158A GeV were recorded and the predicted features were observed at low SPS energies (Alt et al. 2008, Gazdzicki et al. 2011). Last year rich data from the RHIC beam-energy scan programme were released (Kumar 2011, Mohanty 2011). Furthermore, the first results from Pb+Pb collisions at the LHC were revealed (Schukraft et al. 2011, Toia et al. 2011). The plots in figure 1 summarize relevant results that became available in June They show the energy dependence of four hadron-production properties measured in central Pb+Pb (Au+Au) collisions, which reveal structures referred to as the "horn", "kink", "step" and "dale" all located in the SPS energy range. Fig. 1 Heating curves of strongly interacting matter (status mid-2011). The new LHC and RHIC data are included. The horn (top left), kink (top right), step (bottom left) and dale (bottom right). The RHIC results confirm the NA49 measurements at the onset energies while the LHC data demonstrate that the energy dependence of hadron-production properties shows rapid changes only at low SPS energies. A smooth evolution is observed between the top SPS energy (17.2 GeV) and the current energy of the LHC (2.76 TeV). This strongly supports the interpretation of

10 the NA49 structures as arising from the onset of deconfinement. Above the onset energy only a smooth change of the QGP properties with increasing collision energy is expected. The first LHC data thus confirm the following expected effects: an approximate energy independence of the K + /π + ratio above the top SPS energy (Fig. 1 top left); a linear increase of the pion yield per participant with F s NN with the slope defined by the top SPS data (Fig. 1 top right); a monotonic increase of the kaon inverse-slope parameter with energy above the top SPS energy (Fig. 1 bottom left). Ad. 2.??????? ( Joanna S.) 4. Koncepcja i plan badań (jakie są założenia szczegółowych celów badawczych, jaki jest ogólny plan badań, jak zamierza się realizować postawione cele, jakie są wyniki badań wstępnych, wskazujące na słuszność przyjętych założeń) The confirmation of the NA49 measurements and their interpretation in terms of the onset of deconfinement by the new LHC and RHIC data strengthen the arguments for the NA61/SHINE experiment, which will use secondary proton and Be, as well as primary Ar and Xe beams in the SPS beam momentum range (13A 158A GeV/c). The NA61/SHINE detector The NA61/SHINE experiment uses a large acceptance hadron spectrometer located on the H2 beam line in the North Area of CERN. Its main detector components, software, calibration, and analysis methods were inherited from the NA49 experiment. The main tracking devices are four large volume time projection chambers (TPCs), which are capable of detecting up to 70% of all charged particles created in the studied reactions. Two of them, the vertex TPCs, are located in the magnetic field of two super-conducting dipole magnets with maximum bending powers of 9 Tesla meters. Two other tracking devices (MTPC-L and MTPC-R) are positioned downstream of the magnets symmetrically with respect to the beam line. One supplementary small TPC, the gap TPC, is installed on the beam axis between the vertex TPCs. In addition three TOF-walls are positioned behind the TPCs. Two of them (TOF- L/R) were inherited from the NA49 experiment. A forward TOF-wall was added in 2007 to extend the acceptance for particles with p < 3 GeV/c. In 2008 a new TPC readout and DAQ system with about 70 Hz readout frequency were installed. These modifications increased the event rate by factor of about 10.

11 For the ion programme the Projectile Spectator Detector have been assembled and tested. This detector allow precise measurement of the energy of projectile spectators and will provide a single nucleon resolution necessary for the fluctuation studies essential in search for a critical point. Additionally the He beam pipe was installed in order to reduce δ-electron production by the beam by a factor of 10. Charge identification of secondary fragments delivered to the experimental area is performed by a new Cherenkov detector (Z-detector).. Fig. 2 The layout of the NA61/SHINE experiment. Polish groups involved in the NA61/SHINE have made an important contributions to the detector upgrade: In order to achieve good charge identification of secondary ions delivered to NA61, Quartz and Gas Cherenkov counters were build and tested during the 2011 proton run. During measurement with Be secondary the Quartz detector was used achieving the resolution (Seweryn) in the Z=4 region. The 44 modules of the PSD calorimeter were constructed already with significant contribution of the Warsaw University group. The central part of the PSD was tested and calibrated during 2011 data taking period. Due to the participation in the challenging and innovative technological project, Warsaw University group acquired the technology of SiPM operation what should be profitable in other R&D tasks (including industrial applications). The new beam position detectors with larger active area were build. Completely new Detector Control System is under development. Old-fashioned LabVIEWbased system is being replaced with EPICS-based solution integrated with a new Condition Database and alarm system. The responsibility of Polish groups during the data taking include: Maintenance and supervision of the detector control system Maintenance and development of web-based utilities

12 Maintenance and supervision of the gas system of time projection chambers. Supervisions of the beam, maintenance and supervision of the beam position detectors Maintenance and supervision of experimental databasis. Ad. 1. The two-dimensional scan NA61 has already begun a two-dimensional scan in collision energy and the size of the colliding nuclei (figure 2). Data on proton proton interactions at 13, 20, 31, 40, 80, and 158 GeV/c collision energies were recorded in The first physics run with secondary Be beams took place in November/December In year 2012 measurements with Be at 13, 20, and 30 GeV/c. will be performed. Also measurements for proton + Pb interactions will completed. They include high statistics runs at 158 GeV dedicated for a study of hadron production at large transverse momenta. Most important for the programme are runs with primary Ar and Xe beams, expected for 2014 and 2015, respectively. Fig. 3. Data sets already measured and planned to be recorded by NA61/SHINE within the ion program (left) and those recorded by NA49 (right). The green color shows the data already taken. Studying the properties of the onset of deconfinement

13 The properties of the onset of deconfinement will be studied by looking for the kink, horn, step and dale structures in collisions of light and intermediate mass nuclei (Be+Be, Ar+Ca, Xe+La). The results will be compared to these from p+p collisions. We expect that the signatures visible in Pb+Pb/Au+Au collisions will be vanishing with decreasing system size. The horn structure can be observed in <K + >/<π + > ratio, as well as in E s measure which is defined as the average multiplicities of lambdas and kaons divided by the average multiplicity of pions (see [M. Gaździcki, M. Gorenstein, Acta Phys. Polon. B30, 2705 (1999); C. Alt et al. (NA49 Collaboration, Phys. Rev. C77, (2008)]). The step structures was observed by NA49 in m T spectra (inverse slope parameters T and <m T >) of charged kaons, pions and (anti)protons. Therefore, in order to study the properties of the onset of deconfinement we plan to obtain yields and spectra (transverse mass / transverse momentum, rapidity) of many different particle species such as charged kaons, pions, anti(protons), K 0 s, (anti)λ, Σ, Ξ, etc. The NA49 experiment reported an interesting observation in azimuthal angle correlations [M. Szuba (for the NA49 Collaboration)., Nucl. Phys. A830, 159C-162C (2009)]. The near-side peak in the correlation function of two high p T hadrons disappear at lower SPS energies ( hole to jet transition with increasing energy). It is not known yet how and whether this interesting result can be connected with the onset of deconfinement, however we plan to search for such behaviour in p+p, Ar+Ca, and Xe+La collisions recorded by NA61. Resonance production Obtaining the K *, Φ, ρ, and Δ resonances signal in the invariant mass distribution of charged particle daughters, and then measuring the transverse momentum and rapidity distributions of resonances will give a significant contribution to understanding space-time evolution of the relativistic heavy ion collision. The short lifetimes of resonances make it possible that the analysis of their properties gives information about the latest stages of the evolution of the collision. In particular, the (anti)k * production compared to theoretical predictions suggests a substantial duration of the hadron stage of the fireball [T. Anticic et al. (NA49 Collaboration), Phys. Rev. C84, (2011), and references therein]. It was also predicted that the in-medium modifications of resonance properties (masses, widths, branching ratios) can be interpreted as due to partial restoration of chiral symmetry in strongly interacting matter [ R. Pisarski Phys. Lett. 110B, 155 (1982); G. E. Brown, M. Rho, Phys. Rev. Lett. 66, 2720 (1991) and Phys. Rep. 269, 333 (1996)]. Finally, the analysis of resonance production will allow to test the applicability of hadron gas models (HGM); see HGM predictions in [F. Beccatini, J. Manninen, M. Gaździcki, Phys. Rev. C73, (2006)] and K * deviations from HGM predictions in [T. Anticic et al. (NA49 Collaboration), Phys. Rev. C84, (2011), and references therein]. In this project the NA61/SHINE experiment will study resonance production in energy scan in p+p and Be+Be interactions. Fluctuation analysis and critical point search The strategy of critical point search relies mainly on the analysis of fluctuations. It was predicted that multiplicity and transverse momentum fluctuations should be enlarged for systems freezeing out close to the critical point [M. Stephanov, K. Rajagopal, and E. V. Shuryak, Phys. Rev. D60, (1999)]. Also the intermittency signal should be higher in the vicinity of the

14 critical point [N. G. Antoniou et al., Nucl. Phys. A761, 149 (2005), and references therein]. Therefore, a non-monotonic dependence of critical point signal on control parameters (energy, centrality, ion size) can help to locate the critical point of strongly interacting matter. In fact, the NA49 experiment already observed that fluctuations of average p T and multiplicity [K. Grebieszkow (for the NA49 Collaboration), Nucl. Phys. A830, 547C (2009), and references therein], fluctuations of multiplicity of π + π - pairs [T. Anticic et al. (NA49 Collaboration), Phys. Rev. C81, (2010)], and fluctuations of net-proton density [F. Diakonov (for the NA49 Collaboration), CPOD 2011 proc.] tend to a maximum in Si+Si (Si+A) collisions at 158A GeV. This is a strong motivation for the NA61/SHINE experiment where these observables will be analyzed for all systems systems at all SPS energies. The main motivation of studying azimuthal event-by-event fluctuations was to search for plasma instabilities [St. Mrówczyński, Phys. Lett. B314, 118 (1993)], critical point and onset of deconfinement, and flow fluctuations [St. Mrówczyński and E. V. Shuryak, Acta Phys. Polon. B34, 4241 (2003)]. The NA49 data [K. Grebieszkow (for the NA49 Collaboration), arxiv: , and references therein] show no energy dependence of event-by-event azimuthal angle fluctuations. In case of the system size dependence the statistics of NA49 events was too low to judge whether a maximum seen in (semi)central Si+Si interactions at the top SPS energy is significant. Therefore the much larger samples of events recorded by NA61 will allow to perform a precise 2D scan of event-by-event azimuthal fluctuations. Fluctuations in chemical (particle-type) composition of produced hadrons are believed to be sensitive to the properties of matter produced in A+A collisions (e.g. to the phase transition or to appearance of the critical point). The NA49 experiment measured chemical fluctuations in K/π, K/p, p/π ratio and reported an unexpected energy dependence of event-by-event K/p fluctuations [T. Schuster (for NA49 Collaboration), J. Phys. G38, (2011), and references therein]. In NA61 we will study event-by-event chemical fluctuations of different particle species combinations. In this project the analysis of p+p and Be+Be collisions is planned. High p T physics The measurement of nuclear modification factor R AA showed a strong suppression of high p T particles at RHIC and LHC energies. It can be interpreted as a manifestation of parton energy loss in a dense medium. We expect that for lower energy collisions, where deconfined matter is not formed, such suppression should disappear. The p+p data recorder in NA61 together with the existing NA49 Pb+Pb data sets will allow to obtain the energy dependence of nuclear modification factor in the whole SPS energy range. It should be however noticed, that even in A+A collisions the effects of interactions within hot nuclear matter can be somehow masked by the effects observed in cold nuclear matter (i.e. Cronin effect, nuclear shadowing, EMC effect). Therefore it is also important to study the nuclear modification factors in p+a interaction. Thus, in order to have a good reference for the NA49 Pb+Pb data we want to analyze p+p and p+pb data at 13A-158A GeV. With the planned NA61 statistics it will be possible to cover a large range of the inclusive p T spectrum, which was not possible in p+p and p+pb data (at 158 GeV) in the NA49 and the WA98 experiments (ref??).

15 Ad. 2 The measured differential hadron production cross section will be used as input into T2K (Tokai to Kamioka) experiment beam simulation. The T2K is the second generation long baseline neutrino oscillation experiment designed to measure with unprecedented accuracy neutrino oscillation parameters in particular the θ 13 associated with the oscillation from to e. The comparison of difference between the flux and flavor content of the neutrino beam near the neutrino production region and the predicted flux of non oscillated neutrinos in the far detector situated about 290 km away will permit to extract the oscillation parameters. Such comparison requires precise neutrino beam simulation in which an important ingredient is the cross sections for hadron production from proton + carbon interactions at the energy 30 GeV. The T2K neutrino beam is almost pure muon neutrino beam with small (less than 1%) contribution of e, which has to be well controlled since the measurement of e appearance is a main goal of the T2K. The neutrinos are produced in the decays of pions ( ), muons and kaons (K + e e ). Therefore it is important to know precisely the mesons momenta and angular distributions from proton + carbon interactions. brakuje opisu tego rysunku (Joanna) Both neutrino flux and the contamination of e is measured in the near detector but the expected null oscillated neutrino flux would not be the same in the far detector The ratio depends on the momentum vs angle distribution of neutrinos and is predicted using MC simulations. The reliability of the different MC models have be confronted with NA61/SHINE results. It was already partly achieved, but the results of the pilot run analyzed up to now still have not sufficient accuracy both because of limited statistic and systematic errors.

16 The NA61/SHINE collected data with two types of graphit targets a thin one (two cm thick) and a replica of T2K, 90 cm long one. The first one provides information on the primary interaction of incoming protons, the second permit to measure the parameters of particles coming out from different parts of the target. In the later we should extract the three dimension matrix of points as a function of (p,θ,z) where z is the position along the target. One should also take into account the shape of the proton beam in perpendicular directions. Since the differential cross sections for pions and kaons is needed the high statistic experiment was required. About 9.4 M proton on target triggers were collected up to now. We also registered additional an 1 M proton on target triggers in the full magnetic field configuration in order to fully cover the forward production region (up to 30 GeV/c). Finally we should analyze a large sample of events with unprecedented accuracy. 5. Metodyka badań (co stanowi podstawę naukowego warsztatu, na czym będzie polegać analiza i opracowanie wyników badań, jakie urządzenia aparatura zostaną wykorzystane w badaniach, czy podmiot ma do nich bezpośredni dostęp) Ad. 1 Most of the analysis methods performed in NA61/SHINE were already successfully used by the NA49 experiment. The spectra and yields of K +/-, π +/-, and (anti-)protons will be obtained by use of the information about specific energy loss (de/dx) and particle momenta. The analysis will be supplemented by information about particle velocity measured in ToF detectors. The spectra and yields of π - mesons will be additionally obtained using so-called h - method where pions are analysed using not identified spectra of negative hadrons and the remaining small contribution of other particles is extracted by use of Monte Carlo simulations. Due to significant fraction of protons in the sample such method cannot be applied to positive pions. The weakly decaying particles (K 0 s, (anti)λ, Σ, Ξ) will be studied by their decay topologies, it is the secondary vertex (V0) technique will be used. Finally, the resonances (Δ ++, K *, Φ, ρ 0 ) will be searched by combining all possible pairs of decay products originating from the main interaction vertex. The combinatorial background will be obtained by the event mixing method. First π - results relevant to the study of the properties of the onset of deconfinement were already obtained [A. Aduszkiewicz (for the NA61 Collaboration), arxiv: ] for p+c interactions at 31 GeV. They were compared to NA49 results from central Pb+Pb collisions at 30A GeV [C. Alt et al. (NA49 Collaboration), Phys. Rev. C77, (2008)]. The rapidity and m T spectrum was obtained and the inverse slope parameter was fitted to m T spectrum. We also analyzed p+c data at 31 GeV to obtain Λ, K 0 s and Δ ++ spectra. The examples of invariant mass distributions were presented on conferences [A. Aduszkiewicz (for the NA61 Collaboration), arxiv: ; K. Grebieszkow (for the NA61 Collaboration), arxiv: ]. The analysis of p+p collisions at SPS energies is in progress.

17 The azimuthal correlations will be studied for the systems produced in NA61 by use of correlation function C 2 (ΔΦ) [M. Szuba (for the NA49 Collaboration), Nucl. Phys. A830, 159C (2009)]. As the statistics of events recorded by NA61 will be higher than in NA49 we will be able to test several ranges of transverse momentum of trigger and associated particles. The main methods of critical point search in NA61 are also inherited from NA49. For the analysis of multiplicity fluctuations we will use the scaled variance of multplciity distribution ω [see C. Alt et al. (NA49 Collaboration), Phys. Rev. C75, (2007)]. For event-by-event average p T fluctuations Φ pt correlation measure [M. Gaździcki and St. Mrówczyński, Z. Phys. C54, 127 (1992)] will be used (see also [T. Anticic et al. (NA49 Collaboration), Phys. Rev. C70, (2004); T. Anticic et al. (NA49 Collaboration), Phys. Rev. C79, (2009)]). Finally, Φ Φ measure will allow to analyse event-by-event average azimuthal angle fluctuations (see [K. Grebieszkow (for the NA49 Collaboration), arxiv: , and reference therein]). We plan to measure ω, Φ pt, and Φ Φ for all energies and systems recorded by NA61. With the new PSD detector, which has 5 times better resolution than in NA49 (σ(e)/e 0.55/ sqrt(e/(1gev)) ) we will be able to determine centrality of collision with a very high precision. Such precise measurement of the energy of projectile spectators is needed for a tight centrality selection as required for the analysis of fluctuations. The PSD calorimeter will also allow to reconstruct the event reaction plane, what will be very important for future analysis of anisotropic flow. The recently installed helium beam pipes will minimize contamination from spiraling low-energy delta electrons (electrons produced in the gas volume inside the VTPCs from heavy ion beam-gas interactions), which may significantly increase the background in the TPCs and distort measurements of event-by-event fluctuations. For fixed target experiments such as NA61/SHINE, there is always an uncertainty whether the interaction occurs in the target or in some material that surrounds it. In NA61 the problem mostly concerns p+p interactions where the target is 20 cm long liquid hydrogen (LH) cylinder, and contamination may originate for example from collisions with mylar windows of the LH cylinder. All the results (spectra, yields, fluctuations) shown by NA61 are (or are planed to be, for future analysis) corrected for the effects of unwanted non-target interactions. The example of the complete procedure applied for ω and Φ measures can be found in [T. Cetner and K. Grebieszkow (for the NA61 Collaboration), arxiv: ]. Because of the limited acceptance of the NA49 detector in the central rapidity region (midrapidity), the previous multiplicity and p T fluctuation analyzes [T. Anticic et al. (NA49 Collaboration), Phys. Rev. C70, (2004); T. Anticic et al. (NA49 Collaboration), Phys. Rev. C79, (2009); C. Alt et al. (NA49 Collaboration), Phys. Rev. C75, (2007)] were performed in forward rapidity only. However, most of the interesting phenomena, such as fluctuations due to the critical point, are expected to be much better visible when the kinematic acceptance is as large as possible. In principle the magnitudes of both transverse momentum and multiplicity fluctuations (for systems freezeing out at the critical point) are significantly suppressed when the acceptance is limited to forward rapidity only [M. Stephanov, K. Rajagopal, and E. V. Shuryak, Phys. Rev. D60, (1999), and private communication]. Therefore one of the goals of the analysis in NA61 is to find a set of kinematic, quality and geometric cuts, which would allow to include mid-rapidity region in the fluctuation studies. First results on ω and Φ pt in p+c interactions at 31 GeV were shown on conference [K. Grebieszkow (for the NA61

18 Collaboration), arxiv: ]. In this analysis we successfully used complete rapidity range as available in NA61. Apart from the event-by-event measures succesfully used in NA49 we plan to extend the analysis to new variables. In particular the higher moments of multiplicity and average p T fluctuations will be analysed. Higher moments are commonly belived to be more sensitive to the presence of the critical point. A 3 rd moment of Φ pt measure (Φ (3) pt ), which is similarly to Φ pt a strongly intensive measure of fluctuations [St. Mrówczyński, Phys. Lett. B465, 8 (1999)], was preliminary measured in NA49 [P. Seyboth (for the NA49 Collaboration), Nucl. Phys. A , 54 (2011)] but the obtained errors do not allow for any solid conclusions. With the NA61 data sets such analysis may be possible. Moreover, the analysis of completely new strongly intensive measures of fluctuations is also planned. Last year, in publication [M. I. Gorenstein, M. Gaździcki, Phys. Rev. C84, (2011)] the new measures of fluctuations Δ and Σ were introduced. Similarly to Φ measure of fluctuations [M. Gaździcki and St. Mrówczyński, Z. Phys. C54, 127 (1992)], they are strongly intensive (do not depend on the number and on fluctuations of the number of sources composing A+A collision). As the definitions of Δ and Σ measures are based on different moments, Δ and Σ variables can be sensitive to several physics effects in different ways. In fact, previously known Φ measure belongs to Σ -type family. Furthermore, in the definitions of new variables Δ and Σ we can use any two extensive measures, whereas in the original definition of Φ one of them was fixed to be particle multiplicity. In NA61 Δ and Σ measures will be used to obtain transverse momentum and azimuthal angle fluctuations. Several tests on models were already performed [K. Grebieszkow, arxiv: v1] and in particular the Φ, Δ and Σ measures for p T fluctuations in the UrQMD model were obtained for all energies and systems which wil be analyzed within the ion program of NA61. The recently proposed identity method [M. Gaździcki, K. Grebieszkow, M. Maćkowiak, and St. Mrówczyński, Phys. Rev. C83, (2011)] was developed to study event-by-event fluctuations of hadron composition of particles produced in heavy ion collisions. Its main advantage when compared to previously used methods (i.e. σ dyn measure [T. Schuster (for the NA49 Collaboration), J. Phys. G38, (2011), and references therein]) is an analytical and strict way to correct fluctuation measure for misidentification effects. In its first formulation the identity method was performed for a two-component system (i.e. kaons with respect to nonkaons). Next, the method was generalized to the N-component system and for all second moments of identified hadron multiplicities' distributions [M.I. Gorenstein, Phys. Rev. C84, (2011)]. In this analysis the N-component version of the identity method will be used. The energy scan of p+p and Be+Be data will be studied. Theoretical considerations suggest significant intermittency signal in transverse momentum space of di-pions [N. G. Antoniou et al., Nucl. Phys. A761, 149 (2005), and references therein] and net-protons [Y. Hatta and M. A. Stephanov, Phys. Rev. Lett. 91, (2003); F. Diakonov, CPOD 2011 proc.] for systems freezeing out close to the critical point. In fact, such increased signals were indeed reported by NA49 in Si+Si/Si+A collisions at 158A GeV [T. Anticic et al. (NA49 Collaboration), Phys. Rev. C81, (2010), F. Diakonov, CPOD 2011 proc.]. The NA61 experiment will follow the procedure applied by NA49, namely the intermittency signal will be seerched by calculating the combinatorial substracted (by use of mixed events) second factorial moments ΔF 2 (see [T. Anticic et al. (NA49 Collaboration), Phys. Rev. C81, (2010)]). We will study both low mass π + π - pairs (di-pions) and protons. The 2D scan with

19 energy and ion size will allow to find a system and energy for which the magnitude of the measured signal will be the highest and closest to the theoretical value for system freezeing out at the critical point. Ad. 2 The following steps in the analysis of the collected data on p+ carbon at 30GeV have to be performed: 1. Calibration procedure. The large amount of data collected imposes higher requirements on the calibration quality. In particular the assumption that various calibration parameters stay constant for a long period (assumed in the case of the published data collected in 2007) can not be applied any more. Precise evaluation of the data required time dependent corrections. 2. Reconstruction of individual tracks with information on ionization. Improvement of the tracking in the very forward region (θ < 60mrad) is needed. Reconstruction of the full events, vertex fit. In the case of the strange particle the reconstruction of V0 and identification of the kinks on the tracks. The new version of the reconstruction program is being developed (see??). Test of it is required.???? 3. The identification of particle based on the specific ionization losses in the Time Projection Chambers. The fitting procedures in different momentum regions have to be performed. 4. Calculation of correction for acceptance, reconstruction efficiency, decays of mesons and, in the case of pions possible admixture of pions from strange particle decays near the primary vertex. All these corrections should be known as a function of the angle, momentum, possibly particle type and in the case of the long target the position of the point in which the track is leaving the target. 5. The corrections above are based on the Monte Carlo simulation. We intend to study the dependence of the result on the type of event generator. We plan to compare the results obtained with different MC to estimate systematic errors. All the procedures are challenging having in mind only few percent accuracy required In all the phase space region important for T2K experiment. 6. Wymierny, udokumentowany efekt podjętego problemu (zakładany sposób przekazu i upowszechniania wyników publikacje naukowe oraz referaty na konferencjach w Polsce i za granicą, monografie naukowe, rozprawy doktorskie i habilitacyjne, nowe metody i urządzenia badawcze, przewidywany wpływ wyników wykonanych badań na dalszy rozwój nauki)