Posters

2016-10-25
10:20
Development and test of the CO2 evaporative cooling system for the LHCb UT Detector
 Reference: Poster-2016-558 Created: 2016. -1 p Creator(s): Coelli, Simone The upgrade of the LHCb detector, which will take place during the Long Shutdown 2 from mid 2018 to the end of 2019, will extend significantly the physics reach of the experiment by allowing it to run at higher instantaneous luminosity with increased trigger efficiency for a wide range of decay channels. The LHCb upgrade relies on two major changes. Firstly, the full read-out of the front-end electronics, currently limited by a Level-0 trigger to 1 MHz, will be replaced with a 40 MHz trigger system. Secondly, the upgraded LHCb detector will be designed to cope with an increase of the nominal operational luminosity by a factor five compared to the current detector. Compared to the current experiment several subsystems need to be partially rebuilt. Among these the 4 TT planes will be replaced by new high granularity silicon micro-strip planes with an improved coverage of the LHCb acceptance.The new system is called the Upstream Tracker. The radiation length of each UT plane should not exceed the value of 1 % X0. The cooling system has to maintain the temperature of the sensors at -5 °C by removing the heat generated in the ASICs, in the silicon sensors due to self-heating, and in the cables that provide the power to the front-end electronics. The acceptable temperature excursion over the sensor is in the range of 5 °C. The temperature of the ASICs should be kept under 40°C for optimal functioning. The cooling power of the UT detector is rated at 5 kW. An efficient cooling system is necessary for maintaining the temperature of the sensors below - 5 °C in order to reduce the leakage current and prevent thermal runaway in presence of radiation damage. CO2 bi-phase cooling systems have successfully been built and operated for the LHCb VELO particle detectors, which pioneered the use of evaporative CO2 cooling in high energy physics, for the AMS tracker, and recently for the ATLAS Pixel Ineer B-Layer (IBL). They have proved to be very efficient and reliable, providing effective cooling with reduced impact on the material budget. In the UT detector the heat load is dominated by the power dissipation of the read-out ASICs, that are bonded directly to the sensor and positioned close to it in the active tracking volume. Simulation studies based on finite element analysis (FEA), has proved that evaporative CO2 cooling is the optimal choice in terms of cooling effciency and material budget. The CO2 evaporation around - 30 °C take place in cooling pipes embedded in the local support structures: 68 vertical staves, 1.8 m long. High thermally conductive carbon foam in an optimized sandwich structure design, provide a good heat transfer from the sensor and front-end electronics to the cooling pipe. A "snake pipe" design with bent tubes passing underneath the ASICs is currently considered as the baseline solution, providing the maximal heat transfer and the lower and uniform detector temperatures. The material for the pipe is titanium with 2 mm inner diameter and 0.1 mm thickness.The use of a vertical 3 m long "snake pipe" gives the best thermal performance for the detector, but R&D for a system with this geometry was mandatory. R&D activities and real scale test on prototypes have been done, and are in progress, to prove and finalize the design concept. Related links:14th Topical Seminar on Innovative Particle and Radiation Detectors © CERN Geneva Access to files

2016-10-25
09:57
Production and Quality Assurance of a Scintillating Fibre Detector for the LHCb Experiment
 Reference: Poster-2016-557 Created: 2016. -1 p Creator(s): Nieswand, Simon At the Large Hadron Collider (LHC) at CERN, scientists from around the world are using complex detector systems to test the predictions of the Standard Model and to search for indications of new physics. One of those detectors is the LHCb experiment which was specifically designed for the study of heavy hadrons containing bottom and charm quarks (heavy flavour physics). To deal with the increased beam energy and instantaneous luminosity of the LHC after the Long Shutdown 2 in 2018/19, several subsystems of the LHCb detector have to be exchanged and upgraded. For this purpose, a new tracking system that will replace the so-called Inner and Outer Tracker of the current detector is currently being developed and built. The base of this new tracker are 2:5m long scintillating fibres ($\varnothing 250 \mu$) into which light is induced by passing charged particles. The fibres are arranged in six-layered fibre mats which are read out with the help of silicon photomultipliers at the edge of the tracker’s acceptance. The finished tracker will have a spatial resolution below 100 $\mu$ and will cover an area larger than 360m2. To produce the required total of 1100 fibre mats until the beginning of the second Long Shutdown, mass production must be set up at several locations. To assure the quality of the fibre mats, they are subjected to various tests during the production. One of those is a check of the integrity of the fibre matrix inside the mats which is used to look for irregularities and defects. Furthermore, different properties such as light yield, attenuation length, spatial resolution, and detection efficiency are measured with the help of another setup as well as beam tests at carried out at CERN. In this talk, the various studies of the fibre mats are explained in detail and first results are presented. Related links:14th Topical Seminar on Innovative Particle and Radiation Detectors © CERN Geneva Access to files

2016-09-26
15:13
Time-dependent CP-violation measurements in $B^0 \to D^+D^–$ decays at LHCb
 Reference: Poster-2016-556 Created: 2016. -1 p Creator(s): Bel, Lennaert Overconstraining the unitarity triangle is a key goal of LHCb. The excellent time resolution of the detector lends itself to high precision time dependent CP violation measurements. CP observables in $B^0 \to D^{+}D^{‐}$ decays are of great interest as they have the potential to be sensitive to new physics contributions. There is a long¬‐existing tension between results from BaBar and Belle on $B^0 \to D^{+}D^{‐}$. We present results on these CP observables with the full Run 1 dataset. Related links:ICHEP 2016 © CERN Geneva Access to files

2016-09-14
10:17
 Reference: Poster-2016-555 Created: 2016. -1 p Creator(s): Carniti, Paolo The LHCb experiment is devoted to high-precision measurements of CP violation and search for New Physics by studying the decays of beauty and charmed hadrons produced at the Large Hadron Collider (LHC). Two RICH detectors are currently installed and operating successfully, providing a crucial role in the particle identification system of the LHCb experiment. Starting from 2019, the LHCb experiment will be upgraded to operate at higher luminosity, extending its potential for discovery and study of new phenomena. Both the RICH detectors will be upgraded and the entire opto-electronic system has been redesigned in order to cope with the new specifications, namely higher readout rates, and increased occupancies. The new photodetectors, readout electronics, mechanical assembly and cooling system have reached the final phase of development and their performance was thoroughly and successfully validated during several beam test sessions in 2014 and 2015 at the SPS facility at CERN. Details of the test setup and performance results of the opto-electronic readout system will be presented. Related links:RICH 2016 © CERN Geneva Access to files

2016-09-13
10:00
High rate tests of the LHCb RICH Upgrade system
 Reference: Poster-2016-554 Created: 2016. -1 p Creator(s): Blago, Michele Piero One of the biggest challenges for the upgrade of the LHCb RICH detectors from 2020 is to readout the photon detectors at the full 40 MHz rate of the LHC proton-proton collisions. A test facility has been setup at CERN with the purpose to investigate the behaviour of the Multi Anode PMTs, which have been proposed for the upgrade, and their readout electronics at high trigger rates. The MaPMTs are illuminated with a monochromatic laser that can be triggered independently of the readout electronics. A first series of tests, including threshold scans, is performed at low trigger rates (20 kHz) for both the readout and the laser with the purpose to characterise the behaviour of the system under test. Then the trigger rate is increased in two separate steps. First the MaPMTs are exposed to high illumination by triggering the pulsed laser at a high (20 MHz) repetition rate while the DAQ is readout at the same low rate as before. In this way the performance of the MaPMTs and the attached electronics can be evaluated at high laser exposure rate. In the second step both the laser and the DAQ are triggered at the high rate in order to evaluate the full readout chain. Related links:RICH 2016 © CERN Geneva Access to files

2016-09-12
16:37
LHCb upstream tracker
 Reference: Poster-2016-553 Created: 2016. -1 p Creator(s): Artuso, Marina The detector for the LHCb upgrade is designed for 40MHz readout, allowing the experiment to run at an instantaneous luminosity of 2x10^33 cm$^2$s$^-1$. The upgrade of the tracker subsystem in front of the dipole magnet, the Upstream Tracker, is crucial for charged track reconstruction and fast trigger decisions based on a tracking algorithm involving also vertex detector information. The detector consists of 4 planes with a total area of about 8.5m$^2$, made of single sided silicon strip sensors read-out by a novel custom-made ASIC (SALT). Details on the performance of prototype sensors, front-end electronics, near-detector electronics and mechanical components are presented. Related links:ICHEP 2016 Access to files

2016-09-12
10:58
IMPROVEMENT OF THE CERN SPS ELECTROSTATIC SEPTA ION TRAPS
 Reference: Poster-2016-552 Created: 2016. -4 p Creator(s): Balhan, Bruno; Borburgh, Jan; Barlow, Roger Andrew; Raffaele, Graziano At CERN, the SPS synchrotron is equipped with a slow extraction channel towards the fixed target beam lines in the North Area This channel includes five consecutive electrostatic septa, where the field free region and the active high field region are separated by an array of tungsten-rhenium wires. The field-free region provides for the circulating beam, while the high field region is used to deflect the extracted beam. Since the residual gas can be ionized by the orbiting beam, low energy ions could cross the wire array and enter the high field region and cause high voltage breakdown when accelerated onto the cathode. To prevent low energy ions from entering this high electric field region, a vertical field is applied to the orbiting beam using so-called ‘ion traps’ for active protection. The vertical field is created by electrodes placed inside the region containing the circulating beam. Due to electromagnetic coupling onto the ion trap electrodes observed with the high frequency LHC beam (25 ns spaced bunches), the efficiency of the ion traps is greatly reduced. This leads to increased vacuum activity (electron cloud related) as well as high spark rates both in the main field and between the ion trap electrodes and their grounded support. In view of the SPS performance increase required for HL-LHC, this paper highlights the upgrades and improvements required to obtain a stable ion trap field and significantly reduce the number of breakdown events observed with the LHC beam in the accelerator. © CERN Geneva Access to filesAccess to files

2016-09-06
15:33
The early career, gender, and diversity actions at the LHCb Collaboration
 Reference: Poster-2016-551 Keywords:  LHCb Created: 2016. -1 p Creator(s): Rademacker, Jonas; Sciascia, Barbara Numerous surveys of modern particle physics indicate that the discipline is still largely a male pursuit, and one in which women and other marginalised groups continue to face discriminatory practices. The fraction of female particle physicists reduces with each career stage. Early career particle physicists face precarious employment conditions with serial short term contracts, long working hours, the frequent need to relocate, and little prospect for a permanent academic position. There are indications that these employment conditions add to the gender-imbalance in the field, but clearly, this problem directly affects both male and female early career scientists. The LHCb experiment has, as the first (and so far only) LHC experiment, created a dedicated office for Early Career Gender and Diversity (ECGD) (see http://lhcb.web.cern.ch/lhcb/ECGD_Office/ECGD-intro.html ). The ECGD office’s role is to to advise the management on ECGD matters; provide a point of contact for anybody experiencing any kind discrimination, bullying or harassment; collate regular statistics and other relevant information related to gender and, where appropriate, other ECGD matters; organise regular open meetings where ECGD matters are discussed. We report on our first year of experiences as the first ECGD officers in the LHC’s first ECGD office. Amongst the pitfalls of such an office is the potential of being perceived as either inconsequential, or as an external body that is a source of new rules and complications. We will highlight the strategies we adopted in an attempt to circumnavigate these pitfalls, aiming to be (and be seen as) an integral part of LHCb, working with the entire collaboration to achieve an environment in which all members can thrive. We will also discuss a few highlights of our programme in that year, including well-attended plenary meetings at LHCb weeks on topics such as “mentoring”, “(m/p)aternity leave”, “sexual harrassment”, “careers inside and outside HEP” - and the implementation of a mentoring scheme. Related links:ICHEP 2016 © CERN Geneva Access to files

2016-09-05
10:51
LHCb Exotica and Higgs searches
 Reference: Poster-2016-550 Keywords:  LHCb Created: 2016. -1 p Creator(s): Lucchesi, Donatella The unique phase space coverage and features of the LHCb detector at the LHC makes it an ideal environment to probe complementary New Physics parameter regions. In particular, recently developed jet tagging algorithms are ideal for searches involving $b$ and $c$ jets. This poster will review different jet-related exotica searches together with the efforts in the search for a Higgs boson decaying to a pair of heavy quarks. Related links:ICHEP 2016 © CERN Geneva Access to files

2016-09-05
10:41
Flavour tagging of $b$ mesons in $pp$ collisions at LHCb
 Reference: Poster-2016-549 Keywords:  LHCb Created: 2016. -1 p Creator(s): Mueller, Vanessa Flavour tagging, i.e. the inference of the production flavour of reconstructed $b$ hadrons, is essential for precision measurements of decay time-dependent $CP$ violation and of mixing parameters in the the neutral $B$ meson systems. LHC's $pp$ collisions with their high track multiplicities constitute a challenging environment for flavour tagging and demand for new and improved strategies. We present recent progress and new developments in flavour tagging at the LHCb experiment, which will allow for a further improvement of $CP$ violation measurements in decays of $B^0$ and $B_s^0$ mesons. Related links:ICHEP 2016 © CERN Geneva Access to files