Charm in heavy ion collision<\/h3>\r\n The project received funding under the GRIEG competition.<\/p>\n
GRIEG is one of the three calls funded from the Norway and EEA Grants 2014\u20132021 under the Basic Research Programme operated by the National Science Centre. The objective of the programme is to enhance research-based knowledge development, strengthen the Polish-Norwegian research cooperation, improve the quality of publications<\/p>\n
The objectives of the project<\/strong><\/h2>\n\n- measure charm hadron production (mainly D mesons) in central Pb+Pb
\ncollisions<\/li>\n - understand the charm production phenomenology<\/li>\n
- upgrade NA61\/SHINE detector, upgrade of the readout electronics of the Time Projection Chambers part of the NA61\/SHINE detector upgrade during the CERN accelerator Long Shutdown 2 period (2020 and 2021)<\/li>\n<\/ul>\n
\n<\/div>\r\n <\/div>\r\n <\/div>\r\n
\r\n \r\n \r\n Charm in heavy-ion collision<\/strong><\/p>\nThe charm here means property of strongly interacting elementary particles, hadrons, build-out of their sub-elementary fundamental components \u2013 quarks and gluons. These components, with a generic name partons, carry specific charges called colors \u2013 red, green, and blue. Colors are sources of strong interactions binding partons into hadrons, hadrons into nucleons, nucleons into nuclei. The theory describing strong interaction is called Quantum Chromodynamics (QCD). Hadrons are constructed out of partons in such a way that they do not carry any color – so they are called colorless. In other words – the colors of partons are not inherited by hadrons. Colors are not observable. These are different from other charges carried by partons, e.g. electric charge, isotopic spin, and flavors. The flavor here means strangeness possessed by the quark s<\/em>, charm possessed by the quark c<\/em>, true (called also top) by the quark t, <\/em>and beauty (called also bottom) by the quark b<\/em>. Quarks s,c,t,b<\/em>, ordered by the masses, \u00a0are preceded by the lightest quarks u<\/em> (up) and d<\/em> (down) having the same mass, but different components of the isotopic spin\u00a0 \u00b1\u00bd. Gluons are just massless, appearing in eight coloring combinations. Any quark q<\/em> has its antiquark \u00a0\u2013 the same mass, all charges opposite.\u00a0 All hadrons can be systematized as they are build out of pair quark-antiquark q<\/em>\u00a0<\/em>(mesons) or three quarks qqq<\/em> (baryons) \u2013 with quarks glued by gluons.<\/p>\nAlmost all hadrons of the Universe are build out of light quarks u<\/em> and d<\/em>. Higher flavors s,c,t,b<\/em> are formed only under special conditions when \u201cnormal\u201d hadrons collide at high energy. Then the excitation energy is transformed into the production of new particles, and if high enough, into the production of heavy flavor hadrons \u2013 i.e. composed also out of heavy flavor quarks. Such conditions appear \u2013 when Big Bang ignited the Universe, in the cores of stars, and when a beam of particles accelerated in the accelerator hits the target (fixed target experiment) or collides with the opposite beam coming out of the accelerator (collider experiment). Such experiments give the unique possibility to research in a controlled way process and forces on the most fundamental partonic level, to imitate conditions inside star\u2019s core, not excluding some Big Bang conditions.<\/p>\nParticularly interesting situations appear when colliding objects are not single hadrons but nuclei. There is a theoretical possibility, based on QCD suggestions, that within such collision a new form of matter would appear, a kind of hot and dense partonic soup \u2013 called Quark-Gluon Plasma (QGP). Hot means here a temperature of the order \u00a0K\u00b0, dense means 3-15 times normal nuclear matter density. Similar QGP existed during the first milliseconds of Bing Bang, can appear also at the supernova explosions. The main physical problem here, beyond all technological challenges, is to recognize signatures of the QGP appearance. The QGP, composed of deconfined quarks and gluons cools down within s<\/em>, partons pass into confined phase and freshly created hadrons find their way into detectors system. Now, one should decipher out of this experimental data if some signatures of QGP appeared.<\/p>\nNA61\/SHINE, CERN SPS (Super Synchrotron) experiment is a fixed target heavy ion collision experiment. Different sizes of nuclei, from Be+Be till Pb+Pb, are colliding at different energies. The main goal of this project is to upgrade the main detector parts \u2013 the Time Projection Chambers to make possible detection of open charm mesons made of charm\/no-charm pair. There is a well-established hypothesis, that the dumping in the\u00a0 J\/\u03c8 production as compared to the direct charm production is attributed to the QGP medium. \u00a0Unambiguous evidence of the QGP state is still missing, however. The rich and precise results from RHIC and LHC heavy-ion programs did not change the conclusion.<\/p>\n
This charm program requires a tenfold increase in the data taking rate. The NA61\/SHINE charm program is a natural extension of the previous studies of the phase transition to the quark-gluon plasma. It addresses the question of the validity and the limits of statistical and dynamical models of high energy collisions in the new domain of quark mass. The objective of charm hadron production measurements in Pb+Pb collisions is to obtain the \ufb01rst data on the mean number of pairs produced in the full phase space in heavy-ion collisions. Moreover, \ufb01rst results on the collision energy and system size dependence will be provided. This, in particular, should signi\ufb01cantly help to answer the questions:<\/p>\n
\n- What is the mechanism of open charm production?<\/li>\n
- How does the onset of decon\ufb01nement impact open charm production?<\/li>\n
- How does the formation of a quark-gluon plasma impact J\/\u03c8 production?<\/li>\n<\/ul>\n
<\/p>\n
\n<\/div>\r\n <\/div>\r\n <\/div>[\/vc_column][\/vc_row][vc_row][vc_column]\r\n
\r\n \r\n \r\n <\/p>\nParticipating entities:<\/h3>\n\n- University of Silesia in Katowice<\/span><\/li>\n
- \nUniversity of Oslo<\/span><\/div>\n<\/li>\n
- \n<\/span>Warsaw University of Technology<\/div>\n<\/li>\n
- \nUniversity of Bergen, Department of Physics and Technology<\/div>\n<\/li>\n
- \nWestern Norway University of Applied Sciences<\/div>\n<\/li>\n
- \nJagiellonian University in Cracow<\/div>\n<\/li>\n
- \nJan Kochanowski University in Kielce<\/div>\n<\/li>\n
- \nUniversity of Wroc\u0142aw<\/div>\n<\/li>\n
- \nUniversity of Warsaw<\/div>\n<\/li>\n
- \nNational Centre for Nuclear Research<\/div>\n<\/li>\n
- \nThe Henryk Niewodnicza\u0144ski Institute of Nuclear Physics Polish Academy of Sciences<\/div>\n<\/li>\n
- \nAGH University of Science and Technology<\/div>\n<\/li>\n<\/ol>\n
\n<\/div>\r\n <\/div>\r\n <\/div>[\/vc_column][\/vc_row][vc_row][vc_column][vc_single_image image=”2726″ img_size=”large” alignment=”center”][\/vc_column][\/vc_row][vc_row][vc_column]\r\n
\r\n \r\n \r\n <\/p>\nProject initiation meeting (kick-off meeting)<\/h3>\n
Web page<\/a><\/p>\nSlides from meeting<\/p>\n
\n- Phenomenology of open charm production in heavy-ion collisions<\/a>, \u00a0Ionut Arsene Arsene\u00a0(University of Oslo)<\/span><\/span><\/span><\/li>\n
- Open charm measurements in NA61\/SHINE<\/a>\u00a0Pawel Piotr Staszel\u00a0(Jagiellonian University)<\/span><\/span><\/li>\n
- Overview of NA61\/SHINE detector upgrade<\/a>, \u00a0Piotr Podlaski\u00a0(University of Warsaw)<\/span><\/span><\/span><\/li>\n
- Grieg grant for funding of the NA61\/SHINE detector upgrade<\/a>, Seweryn Kowalski\u00a0(University of Silesia)<\/span><\/span><\/li>\n<\/ul>\n
<\/h2>\n\n- \n
Project main tasks and activities in 2020 and 2021:<\/strong><\/h2>\n<\/li>\n<\/ul>\nUpgrade of the Time Projections Chambers<\/h3>\n
The significant modification of the NA61\/SHINE spectrometer was planned for 2019 – 2022. The upgrade was motivated by the charm program, which requires a tenfold increase of the data taking the rate to about 1 kHz – the main topic connected with this upgrade and covered by this project is the upgrade of the TPCs chambers. The following tasks cover this topic:<\/p>\n
\n- Development of a 3D model of detectors with electronics, cooling system, and mechanical support elements<\/li>\n
- Design, manufacturing, and mounting of the mechanical support of electronics and cooling elements<\/li>\n
- Design and mounting of the low-voltage system<\/li>\n
- Design, construction, and maintenance of the readout chain<\/li>\n
- Maintenance and further development of the detector control system<\/li>\n
- Maintenance and upgrade of the gas system<\/li>\n<\/ul>\n
Test of the detector<\/h3>\n
Before the test on the beam, the FEC was tested to check each readout element for noise and connectivity.
\nThe connectivity to the readout chambers was tested using the calibration pulser system. The LV system (Wiener PS) in its final setup was used for the tests described above. Moreover, the comparison of the noise level to the one measured previously by ALICE (where this electronics operated). The noise level is generally higher than in ALICE because the protection circuitry and the trace length on the adapter circuit boards introduce additional noise.<\/p>\n
The TPC was tested on the beam in the fall of 2021 with the magnetic field switched on, and the first tracks were observed. Analyzing the data collected during the test allows for tuning the detector parameters.<\/p>\n
Software<\/h3>\n
The new Trigger and Data AcQuisition system (TDAQ) were prepared. All crucial components of the data flow software have been developed and tested. We are now in the stage of configuration fine-tuning. In addition, new features are being added, such as a web-based user interface and additional monitoring. From the point of view of the calibration and analysis software, the implementation of new software for calibration of the energy loss (dE\/dx) in the TPC’s where done. A preliminary validation on p+Pb data at 158 GeV\/c was performed, and an automation system was built to facilitate the unsupervised running of the multiple calibration steps.
\nAdditionally, a detailed inspection of gain variations over the TPCs has been performed by means of pad gain maps per TPC sector, obtained from charge spectra per pad resulting from injection and subsequent decay of the 83Kr isotope in the chambers. The upgraded TPC electronics deliver data in a new raw data format, and corresponding decoding and parsing software infrastructure must be available in the SHINE Offline Framework. During the TPC electronics testing, a detector raw data parser was written and used for the quality assessment of TPC raw data. This parser will be moved into the Offline Framework I\/O libraries. A second parser was written to translate raw TPC front-end electronics channels to physical TPC pad objects, a crucial step toward data reconstruction.
\nThe work connected with Monte Carlo simulations was mostly devoted to implementing the new version of the GEANT 4.0, a toolkit for the simulation of the passage of particles through matter, and implementing the Kalman Filter-based tracking algorithm.<\/p>\n
The most critical achievement regarding the maintenance of IT resources was the transition from Jenkins to GitLab CI. This provided versioning of the CI setup, the tested software, automatic checks of all branches, and the division of pipelines into stages. Four software releases were delivered, supporting the development of the new reconstruction software, improvements in the Monte Carlo, and providing multiple bug fixes and optimizations.<\/p>\n
Charm physics<\/h3>\n
The main activities were mainly connected with analyzing the pilot data collected before the upgrade of the TPCs. Moreover, analysis to obtain the yield of the open charm production, the pilot data with different statistical and string models, and previous measurements (the NA60\/NA50 experiment) were performed. The work is still in progress.<\/p>\n
\n- \n
Project main tasks and activities in 2023:<\/strong><\/h2>\n<\/li>\n<\/ul>\nUpgrade of the Time Projections Chambers<\/h3>\n
The LS2 detector upgrade was completed. The new and upgraded detectors were commissioned using hadron beams in spring 2022. The commissioning with 150A GeV\/c Pb beam and the first data taking on open charm production in Pb+Pb collisions was done in \u00a0November 2022.<\/p>\n
The physics run proved that the primary goal of the upgrade was achieved. The maximum data-taking rate reached 1.6 kHz, much higher than the assumed 1 kHz. The upgrade of the TPC electronics has influenced the quality of collected data, as shown in the figure below:<\/p>\n
![](\"https:\/\/us.edu.pl\/instytut\/ifiz\/wp-content\/uploads\/sites\/39\/Bez-kategorii\/Picture1-1.png\")
<\/p>\n
The considerable effort the participants invested in the detector upgrade opens new options for physics measurements and ensures the operation of the experiment for the next few years.<\/p>\n
Software<\/h3>\n
The reconstruction and calibration software is continuously maintained and developed. Significant effort was dedicated to developing the software for the upgraded detector. This has allowed efficient online and offline monitoring during the physics data taking in 2022, as well as the Kr calibration of the upgraded Time Projection Chambers.<\/p>\n
Charm physics<\/h3>\n
In 2023, the Pb beam at a momentum of 150A GeV\/c was delivered to the NA61\/SHINE experiment on the 16th of November. After one week of setup, the production data taking started with a 3 mm lead target, providing 6% interaction probability. The data were taken with the unbiased interaction T2 trigger (identified interaction) and beam T1 trigger (identified beam) scaled down by a factor of 100. The total number of interaction trigger events collected during one week of the production data-taking period amounts to 50 million. This includes about 30 million Pb+Pb collisions. It was the first NA61\/SHINE measurement with a lead ion beam performed after the hardware upgrade during the Long Shutdown 2<\/p>\n
Project meeting (in medium meeting)<\/h3>\n
The project received funding under the GRIEG competition.<\/p>\n
GRIEG is one of the three calls funded from the Norway and EEA Grants 2014\u20132021 under the Basic Research Programme operated by the National Science Centre. The objective of the programme is to enhance research-based knowledge development, strengthen the Polish-Norwegian research cooperation, improve the quality of publications<\/p>\n
The objectives of the project<\/strong><\/h2>\n\n- measure charm hadron production (mainly D mesons) in central Pb+Pb
\ncollisions<\/li>\n - understand the charm production phenomenology<\/li>\n
- upgrade NA61\/SHINE detector, upgrade of the readout electronics of the Time Projection Chambers part of the NA61\/SHINE detector upgrade during the CERN accelerator Long Shutdown 2 period (2020 and 2021)<\/li>\n<\/ul>\n
\n<\/div>\r\n <\/div>\r\n <\/div>\r\n
\r\n \r\n \r\n Charm in heavy-ion collision<\/strong><\/p>\nThe charm here means property of strongly interacting elementary particles, hadrons, build-out of their sub-elementary fundamental components \u2013 quarks and gluons. These components, with a generic name partons, carry specific charges called colors \u2013 red, green, and blue. Colors are sources of strong interactions binding partons into hadrons, hadrons into nucleons, nucleons into nuclei. The theory describing strong interaction is called Quantum Chromodynamics (QCD). Hadrons are constructed out of partons in such a way that they do not carry any color – so they are called colorless. In other words – the colors of partons are not inherited by hadrons. Colors are not observable. These are different from other charges carried by partons, e.g. electric charge, isotopic spin, and flavors. The flavor here means strangeness possessed by the quark s<\/em>, charm possessed by the quark c<\/em>, true (called also top) by the quark t, <\/em>and beauty (called also bottom) by the quark b<\/em>. Quarks s,c,t,b<\/em>, ordered by the masses, \u00a0are preceded by the lightest quarks u<\/em> (up) and d<\/em> (down) having the same mass, but different components of the isotopic spin\u00a0 \u00b1\u00bd. Gluons are just massless, appearing in eight coloring combinations. Any quark q<\/em> has its antiquark \u00a0\u2013 the same mass, all charges opposite.\u00a0 All hadrons can be systematized as they are build out of pair quark-antiquark q<\/em>\u00a0<\/em>(mesons) or three quarks qqq<\/em> (baryons) \u2013 with quarks glued by gluons.<\/p>\nAlmost all hadrons of the Universe are build out of light quarks u<\/em> and d<\/em>. Higher flavors s,c,t,b<\/em> are formed only under special conditions when \u201cnormal\u201d hadrons collide at high energy. Then the excitation energy is transformed into the production of new particles, and if high enough, into the production of heavy flavor hadrons \u2013 i.e. composed also out of heavy flavor quarks. Such conditions appear \u2013 when Big Bang ignited the Universe, in the cores of stars, and when a beam of particles accelerated in the accelerator hits the target (fixed target experiment) or collides with the opposite beam coming out of the accelerator (collider experiment). Such experiments give the unique possibility to research in a controlled way process and forces on the most fundamental partonic level, to imitate conditions inside star\u2019s core, not excluding some Big Bang conditions.<\/p>\nParticularly interesting situations appear when colliding objects are not single hadrons but nuclei. There is a theoretical possibility, based on QCD suggestions, that within such collision a new form of matter would appear, a kind of hot and dense partonic soup \u2013 called Quark-Gluon Plasma (QGP). Hot means here a temperature of the order \u00a0K\u00b0, dense means 3-15 times normal nuclear matter density. Similar QGP existed during the first milliseconds of Bing Bang, can appear also at the supernova explosions. The main physical problem here, beyond all technological challenges, is to recognize signatures of the QGP appearance. The QGP, composed of deconfined quarks and gluons cools down within s<\/em>, partons pass into confined phase and freshly created hadrons find their way into detectors system. Now, one should decipher out of this experimental data if some signatures of QGP appeared.<\/p>\nNA61\/SHINE, CERN SPS (Super Synchrotron) experiment is a fixed target heavy ion collision experiment. Different sizes of nuclei, from Be+Be till Pb+Pb, are colliding at different energies. The main goal of this project is to upgrade the main detector parts \u2013 the Time Projection Chambers to make possible detection of open charm mesons made of charm\/no-charm pair. There is a well-established hypothesis, that the dumping in the\u00a0 J\/\u03c8 production as compared to the direct charm production is attributed to the QGP medium. \u00a0Unambiguous evidence of the QGP state is still missing, however. The rich and precise results from RHIC and LHC heavy-ion programs did not change the conclusion.<\/p>\n
This charm program requires a tenfold increase in the data taking rate. The NA61\/SHINE charm program is a natural extension of the previous studies of the phase transition to the quark-gluon plasma. It addresses the question of the validity and the limits of statistical and dynamical models of high energy collisions in the new domain of quark mass. The objective of charm hadron production measurements in Pb+Pb collisions is to obtain the \ufb01rst data on the mean number of pairs produced in the full phase space in heavy-ion collisions. Moreover, \ufb01rst results on the collision energy and system size dependence will be provided. This, in particular, should signi\ufb01cantly help to answer the questions:<\/p>\n
\n- What is the mechanism of open charm production?<\/li>\n
- How does the onset of decon\ufb01nement impact open charm production?<\/li>\n
- How does the formation of a quark-gluon plasma impact J\/\u03c8 production?<\/li>\n<\/ul>\n
<\/p>\n
\n<\/div>\r\n <\/div>\r\n <\/div>[\/vc_column][\/vc_row][vc_row][vc_column]\r\n
\r\n \r\n \r\n <\/p>\nParticipating entities:<\/h3>\n\n- University of Silesia in Katowice<\/span><\/li>\n
- \nUniversity of Oslo<\/span><\/div>\n<\/li>\n
- \n<\/span>Warsaw University of Technology<\/div>\n<\/li>\n
- \nUniversity of Bergen, Department of Physics and Technology<\/div>\n<\/li>\n
- \nWestern Norway University of Applied Sciences<\/div>\n<\/li>\n
- \nJagiellonian University in Cracow<\/div>\n<\/li>\n
- \nJan Kochanowski University in Kielce<\/div>\n<\/li>\n
- \nUniversity of Wroc\u0142aw<\/div>\n<\/li>\n
- \nUniversity of Warsaw<\/div>\n<\/li>\n
- \nNational Centre for Nuclear Research<\/div>\n<\/li>\n
- \nThe Henryk Niewodnicza\u0144ski Institute of Nuclear Physics Polish Academy of Sciences<\/div>\n<\/li>\n
- \nAGH University of Science and Technology<\/div>\n<\/li>\n<\/ol>\n
\n<\/div>\r\n <\/div>\r\n <\/div>[\/vc_column][\/vc_row][vc_row][vc_column][vc_single_image image=”2726″ img_size=”large” alignment=”center”][\/vc_column][\/vc_row][vc_row][vc_column]\r\n
\r\n \r\n \r\n <\/p>\nProject initiation meeting (kick-off meeting)<\/h3>\n
Web page<\/a><\/p>\nSlides from meeting<\/p>\n
\n- Phenomenology of open charm production in heavy-ion collisions<\/a>, \u00a0Ionut Arsene Arsene\u00a0(University of Oslo)<\/span><\/span><\/span><\/li>\n
- Open charm measurements in NA61\/SHINE<\/a>\u00a0Pawel Piotr Staszel\u00a0(Jagiellonian University)<\/span><\/span><\/li>\n
- Overview of NA61\/SHINE detector upgrade<\/a>, \u00a0Piotr Podlaski\u00a0(University of Warsaw)<\/span><\/span><\/span><\/li>\n
- Grieg grant for funding of the NA61\/SHINE detector upgrade<\/a>, Seweryn Kowalski\u00a0(University of Silesia)<\/span><\/span><\/li>\n<\/ul>\n
<\/h2>\n\n- \n
Project main tasks and activities in 2020 and 2021:<\/strong><\/h2>\n<\/li>\n<\/ul>\nUpgrade of the Time Projections Chambers<\/h3>\n
The significant modification of the NA61\/SHINE spectrometer was planned for 2019 – 2022. The upgrade was motivated by the charm program, which requires a tenfold increase of the data taking the rate to about 1 kHz – the main topic connected with this upgrade and covered by this project is the upgrade of the TPCs chambers. The following tasks cover this topic:<\/p>\n
\n- Development of a 3D model of detectors with electronics, cooling system, and mechanical support elements<\/li>\n
- Design, manufacturing, and mounting of the mechanical support of electronics and cooling elements<\/li>\n
- Design and mounting of the low-voltage system<\/li>\n
- Design, construction, and maintenance of the readout chain<\/li>\n
- Maintenance and further development of the detector control system<\/li>\n
- Maintenance and upgrade of the gas system<\/li>\n<\/ul>\n
Test of the detector<\/h3>\n
Before the test on the beam, the FEC was tested to check each readout element for noise and connectivity.
\nThe connectivity to the readout chambers was tested using the calibration pulser system. The LV system (Wiener PS) in its final setup was used for the tests described above. Moreover, the comparison of the noise level to the one measured previously by ALICE (where this electronics operated). The noise level is generally higher than in ALICE because the protection circuitry and the trace length on the adapter circuit boards introduce additional noise.<\/p>\n
The TPC was tested on the beam in the fall of 2021 with the magnetic field switched on, and the first tracks were observed. Analyzing the data collected during the test allows for tuning the detector parameters.<\/p>\n
Software<\/h3>\n
The new Trigger and Data AcQuisition system (TDAQ) were prepared. All crucial components of the data flow software have been developed and tested. We are now in the stage of configuration fine-tuning. In addition, new features are being added, such as a web-based user interface and additional monitoring. From the point of view of the calibration and analysis software, the implementation of new software for calibration of the energy loss (dE\/dx) in the TPC’s where done. A preliminary validation on p+Pb data at 158 GeV\/c was performed, and an automation system was built to facilitate the unsupervised running of the multiple calibration steps.
\nAdditionally, a detailed inspection of gain variations over the TPCs has been performed by means of pad gain maps per TPC sector, obtained from charge spectra per pad resulting from injection and subsequent decay of the 83Kr isotope in the chambers. The upgraded TPC electronics deliver data in a new raw data format, and corresponding decoding and parsing software infrastructure must be available in the SHINE Offline Framework. During the TPC electronics testing, a detector raw data parser was written and used for the quality assessment of TPC raw data. This parser will be moved into the Offline Framework I\/O libraries. A second parser was written to translate raw TPC front-end electronics channels to physical TPC pad objects, a crucial step toward data reconstruction.
\nThe work connected with Monte Carlo simulations was mostly devoted to implementing the new version of the GEANT 4.0, a toolkit for the simulation of the passage of particles through matter, and implementing the Kalman Filter-based tracking algorithm.<\/p>\n
The most critical achievement regarding the maintenance of IT resources was the transition from Jenkins to GitLab CI. This provided versioning of the CI setup, the tested software, automatic checks of all branches, and the division of pipelines into stages. Four software releases were delivered, supporting the development of the new reconstruction software, improvements in the Monte Carlo, and providing multiple bug fixes and optimizations.<\/p>\n
Charm physics<\/h3>\n
The main activities were mainly connected with analyzing the pilot data collected before the upgrade of the TPCs. Moreover, analysis to obtain the yield of the open charm production, the pilot data with different statistical and string models, and previous measurements (the NA60\/NA50 experiment) were performed. The work is still in progress.<\/p>\n
\n- \n
Project main tasks and activities in 2023:<\/strong><\/h2>\n<\/li>\n<\/ul>\nUpgrade of the Time Projections Chambers<\/h3>\n
The LS2 detector upgrade was completed. The new and upgraded detectors were commissioned using hadron beams in spring 2022. The commissioning with 150A GeV\/c Pb beam and the first data taking on open charm production in Pb+Pb collisions was done in \u00a0November 2022.<\/p>\n
The physics run proved that the primary goal of the upgrade was achieved. The maximum data-taking rate reached 1.6 kHz, much higher than the assumed 1 kHz. The upgrade of the TPC electronics has influenced the quality of collected data, as shown in the figure below:<\/p>\n
<\/p>\n
The considerable effort the participants invested in the detector upgrade opens new options for physics measurements and ensures the operation of the experiment for the next few years.<\/p>\n
Software<\/h3>\n
The reconstruction and calibration software is continuously maintained and developed. Significant effort was dedicated to developing the software for the upgraded detector. This has allowed efficient online and offline monitoring during the physics data taking in 2022, as well as the Kr calibration of the upgraded Time Projection Chambers.<\/p>\n
Charm physics<\/h3>\n
In 2023, the Pb beam at a momentum of 150A GeV\/c was delivered to the NA61\/SHINE experiment on the 16th of November. After one week of setup, the production data taking started with a 3 mm lead target, providing 6% interaction probability. The data were taken with the unbiased interaction T2 trigger (identified interaction) and beam T1 trigger (identified beam) scaled down by a factor of 100. The total number of interaction trigger events collected during one week of the production data-taking period amounts to 50 million. This includes about 30 million Pb+Pb collisions. It was the first NA61\/SHINE measurement with a lead ion beam performed after the hardware upgrade during the Long Shutdown 2<\/p>\n
Project meeting (in medium meeting)<\/h3>\n
\ncollisions<\/li>\n
\n<\/div>\r\n <\/div>\r\n <\/div>\r\n
Charm in heavy-ion collision<\/strong><\/p>\n The charm here means property of strongly interacting elementary particles, hadrons, build-out of their sub-elementary fundamental components \u2013 quarks and gluons. These components, with a generic name partons, carry specific charges called colors \u2013 red, green, and blue. Colors are sources of strong interactions binding partons into hadrons, hadrons into nucleons, nucleons into nuclei. The theory describing strong interaction is called Quantum Chromodynamics (QCD). Hadrons are constructed out of partons in such a way that they do not carry any color – so they are called colorless. In other words – the colors of partons are not inherited by hadrons. Colors are not observable. These are different from other charges carried by partons, e.g. electric charge, isotopic spin, and flavors. The flavor here means strangeness possessed by the quark s<\/em>, charm possessed by the quark c<\/em>, true (called also top) by the quark t, <\/em>and beauty (called also bottom) by the quark b<\/em>. Quarks s,c,t,b<\/em>, ordered by the masses, \u00a0are preceded by the lightest quarks u<\/em> (up) and d<\/em> (down) having the same mass, but different components of the isotopic spin\u00a0 \u00b1\u00bd. Gluons are just massless, appearing in eight coloring combinations. Any quark q<\/em> has its antiquark \u00a0\u2013 the same mass, all charges opposite.\u00a0 All hadrons can be systematized as they are build out of pair quark-antiquark q<\/em>\u00a0<\/em>(mesons) or three quarks qqq<\/em> (baryons) \u2013 with quarks glued by gluons.<\/p>\n Almost all hadrons of the Universe are build out of light quarks u<\/em> and d<\/em>. Higher flavors s,c,t,b<\/em> are formed only under special conditions when \u201cnormal\u201d hadrons collide at high energy. Then the excitation energy is transformed into the production of new particles, and if high enough, into the production of heavy flavor hadrons \u2013 i.e. composed also out of heavy flavor quarks. Such conditions appear \u2013 when Big Bang ignited the Universe, in the cores of stars, and when a beam of particles accelerated in the accelerator hits the target (fixed target experiment) or collides with the opposite beam coming out of the accelerator (collider experiment). Such experiments give the unique possibility to research in a controlled way process and forces on the most fundamental partonic level, to imitate conditions inside star\u2019s core, not excluding some Big Bang conditions.<\/p>\n Particularly interesting situations appear when colliding objects are not single hadrons but nuclei. There is a theoretical possibility, based on QCD suggestions, that within such collision a new form of matter would appear, a kind of hot and dense partonic soup \u2013 called Quark-Gluon Plasma (QGP). Hot means here a temperature of the order \u00a0K\u00b0, dense means 3-15 times normal nuclear matter density. Similar QGP existed during the first milliseconds of Bing Bang, can appear also at the supernova explosions. The main physical problem here, beyond all technological challenges, is to recognize signatures of the QGP appearance. The QGP, composed of deconfined quarks and gluons cools down within s<\/em>, partons pass into confined phase and freshly created hadrons find their way into detectors system. Now, one should decipher out of this experimental data if some signatures of QGP appeared.<\/p>\n NA61\/SHINE, CERN SPS (Super Synchrotron) experiment is a fixed target heavy ion collision experiment. Different sizes of nuclei, from Be+Be till Pb+Pb, are colliding at different energies. The main goal of this project is to upgrade the main detector parts \u2013 the Time Projection Chambers to make possible detection of open charm mesons made of charm\/no-charm pair. There is a well-established hypothesis, that the dumping in the\u00a0 J\/\u03c8 production as compared to the direct charm production is attributed to the QGP medium. \u00a0Unambiguous evidence of the QGP state is still missing, however. The rich and precise results from RHIC and LHC heavy-ion programs did not change the conclusion.<\/p>\n This charm program requires a tenfold increase in the data taking rate. The NA61\/SHINE charm program is a natural extension of the previous studies of the phase transition to the quark-gluon plasma. It addresses the question of the validity and the limits of statistical and dynamical models of high energy collisions in the new domain of quark mass. The objective of charm hadron production measurements in Pb+Pb collisions is to obtain the \ufb01rst data on the mean number of pairs produced in the full phase space in heavy-ion collisions. Moreover, \ufb01rst results on the collision energy and system size dependence will be provided. This, in particular, should signi\ufb01cantly help to answer the questions:<\/p>\n <\/p>\n \n<\/div>\r\n <\/div>\r\n <\/div>[\/vc_column][\/vc_row][vc_row][vc_column]\r\n \n<\/div>\r\n <\/div>\r\n <\/div>[\/vc_column][\/vc_row][vc_row][vc_column][vc_single_image image=”2726″ img_size=”large” alignment=”center”][\/vc_column][\/vc_row][vc_row][vc_column]\r\n Web page<\/a><\/p>\n Slides from meeting<\/p>\n The significant modification of the NA61\/SHINE spectrometer was planned for 2019 – 2022. The upgrade was motivated by the charm program, which requires a tenfold increase of the data taking the rate to about 1 kHz – the main topic connected with this upgrade and covered by this project is the upgrade of the TPCs chambers. The following tasks cover this topic:<\/p>\n Before the test on the beam, the FEC was tested to check each readout element for noise and connectivity. The TPC was tested on the beam in the fall of 2021 with the magnetic field switched on, and the first tracks were observed. Analyzing the data collected during the test allows for tuning the detector parameters.<\/p>\n The new Trigger and Data AcQuisition system (TDAQ) were prepared. All crucial components of the data flow software have been developed and tested. We are now in the stage of configuration fine-tuning. In addition, new features are being added, such as a web-based user interface and additional monitoring. From the point of view of the calibration and analysis software, the implementation of new software for calibration of the energy loss (dE\/dx) in the TPC’s where done. A preliminary validation on p+Pb data at 158 GeV\/c was performed, and an automation system was built to facilitate the unsupervised running of the multiple calibration steps. The most critical achievement regarding the maintenance of IT resources was the transition from Jenkins to GitLab CI. This provided versioning of the CI setup, the tested software, automatic checks of all branches, and the division of pipelines into stages. Four software releases were delivered, supporting the development of the new reconstruction software, improvements in the Monte Carlo, and providing multiple bug fixes and optimizations.<\/p>\n The main activities were mainly connected with analyzing the pilot data collected before the upgrade of the TPCs. Moreover, analysis to obtain the yield of the open charm production, the pilot data with different statistical and string models, and previous measurements (the NA60\/NA50 experiment) were performed. The work is still in progress.<\/p>\n The LS2 detector upgrade was completed. The new and upgraded detectors were commissioned using hadron beams in spring 2022. The commissioning with 150A GeV\/c Pb beam and the first data taking on open charm production in Pb+Pb collisions was done in \u00a0November 2022.<\/p>\n The physics run proved that the primary goal of the upgrade was achieved. The maximum data-taking rate reached 1.6 kHz, much higher than the assumed 1 kHz. The upgrade of the TPC electronics has influenced the quality of collected data, as shown in the figure below:<\/p>\n The considerable effort the participants invested in the detector upgrade opens new options for physics measurements and ensures the operation of the experiment for the next few years.<\/p>\n The reconstruction and calibration software is continuously maintained and developed. Significant effort was dedicated to developing the software for the upgraded detector. This has allowed efficient online and offline monitoring during the physics data taking in 2022, as well as the Kr calibration of the upgraded Time Projection Chambers.<\/p>\n In 2023, the Pb beam at a momentum of 150A GeV\/c was delivered to the NA61\/SHINE experiment on the 16th of November. After one week of setup, the production data taking started with a 3 mm lead target, providing 6% interaction probability. The data were taken with the unbiased interaction T2 trigger (identified interaction) and beam T1 trigger (identified beam) scaled down by a factor of 100. The total number of interaction trigger events collected during one week of the production data-taking period amounts to 50 million. This includes about 30 million Pb+Pb collisions. It was the first NA61\/SHINE measurement with a lead ion beam performed after the hardware upgrade during the Long Shutdown 2<\/p>\n\n
Participating entities:<\/h3>\n
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Project initiation meeting (kick-off meeting)<\/h3>\n
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<\/h2>\n
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Project main tasks and activities in 2020 and 2021:<\/strong><\/h2>\n<\/li>\n<\/ul>\n
Upgrade of the Time Projections Chambers<\/h3>\n
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Test of the detector<\/h3>\n
\nThe connectivity to the readout chambers was tested using the calibration pulser system. The LV system (Wiener PS) in its final setup was used for the tests described above. Moreover, the comparison of the noise level to the one measured previously by ALICE (where this electronics operated). The noise level is generally higher than in ALICE because the protection circuitry and the trace length on the adapter circuit boards introduce additional noise.<\/p>\nSoftware<\/h3>\n
\nAdditionally, a detailed inspection of gain variations over the TPCs has been performed by means of pad gain maps per TPC sector, obtained from charge spectra per pad resulting from injection and subsequent decay of the 83Kr isotope in the chambers. The upgraded TPC electronics deliver data in a new raw data format, and corresponding decoding and parsing software infrastructure must be available in the SHINE Offline Framework. During the TPC electronics testing, a detector raw data parser was written and used for the quality assessment of TPC raw data. This parser will be moved into the Offline Framework I\/O libraries. A second parser was written to translate raw TPC front-end electronics channels to physical TPC pad objects, a crucial step toward data reconstruction.
\nThe work connected with Monte Carlo simulations was mostly devoted to implementing the new version of the GEANT 4.0, a toolkit for the simulation of the passage of particles through matter, and implementing the Kalman Filter-based tracking algorithm.<\/p>\nCharm physics<\/h3>\n
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Project main tasks and activities in 2023:<\/strong><\/h2>\n<\/li>\n<\/ul>\n
Upgrade of the Time Projections Chambers<\/h3>\n
<\/p>\nSoftware<\/h3>\n
Charm physics<\/h3>\n
Project meeting (in medium meeting)<\/h3>\n