Readout Electronics for the Upgraded ITS Detector in the ALICE Experiment

ALICE is undergoing upgrades during the Long Shutdown (LS) 2 of the LHC to improve its performance and capabilities, and to prepare the experiment for the increases in luminosity provided by the LHC in Run 3 and Run 4. One of the most extensive upgrades of the experiment (and the topic of this thesis) is the replacement of the Inner Tracking System (ITS) in its entirety with a new and upgraded system. The new ITS consists exclusively of pixel sensors organized in seven cylindrical layers, and offers significantly improved tracking capabilities at higher interaction rates. And in contrast to the previous system, which would only trigger on a subset of the available events that were deemed “interesting”, the upgraded ITS will capture all events; either in a triggered mode using minimum-bias triggers, or in a “trigger-less” continuous mode where event data is continuously read out. The key component of the upgrade is a novel pixel sensor chip, the ALPIDE, which was developed at CERN specifically for the ALICE ITS upgrade. The seven layers of the ITS is assembled from sub-assemblies of sensor chips referred to as staves, and the entire detector consists of 24 120 chips in total. The staves come in three different configurations; they range from 9 chips per stave for the innermost layers, and up to 196 chips per stave in the outer layers. The number of control and data links, as well as the bit-rate of the data links, differs widely between the staves as well. Data readout from the high-speed copper links of the detector requires dedicated readout electronics in the vicinity of the detector. The core component of this system is the FPGA-based Readout Unit (RU). It facilitates the readout of the data links and transfer data to the experiment’s server farms via optical links; provides control, configuration and monitoring of the sensor chips using the same optical links, as well as over CAN-bus for redundancy; distributes trigger signals to the sensor, either by forwarding the minimum-bias triggers of the experiment, or by local generation of trigger pulses for the continuous mode. And the field-programmable devices of the RU allows for future updates and changes of functionality, which can be performed remotely via several redundant paths to the RUs. This is an important feature, since the RUs are not easily accessible when they are installed in the cavern of the experiment and will be exposed to radiation when the LHC is in operation. Radiation tolerance has been an important concern during the development of the FPGA designs, as well as the RU hardware itself, since radiation-induced errors in the RUs are expected during operation. Techniques such as Triple Modular Redundancy (TMR) were used in the FPGA designs to mitigate these effects. One example is the radiation tolerant CAN controller design which is introduced in this thesis. A different challenge, which is also addressed in this thesis, is the monitoring of internal status and quantities such as temperature and voltage in the ALPIDE chips. This is performed over the ALPIDE’s control bus, but must be carefully coordinated as the control bus is also used for triggers. The detector and readout electronics are designed to operate under a wide set of conditions. Considering events from Pb–Pb collisions, which may have thousands of pixel hits in the detector, a typical pp event has comparatively few pixel hits, but the collision rate is significantly higher for pp runs than it is for Pb–Pb runs. And the detector can be used with two triggering modes, where the continuous trigger mode has additional parameters for trigger period. A simulation model of the ALPIDE and ITS, presented in this thesis, was developed to simulate the readout performance and efficiency of the detector under a wide set of circumstances. The simulated results show that the detector should perform with a high efficiency at the collision rates that are planned for Run 3. Initial plans for a dedicated hardware, to handle and coordinate busy status for the detector, was deemed superfluous and the plans were canceled based on these results. Collision rates higher than those planned for Run 3 were also simulated to yield parameters for optimal performance at those rates. For the RU, which was designed to interface to three widely different stave designs, the simulations quantified the amount of data the readout electronics will have to handle depending on the detector layer and operating conditions. Furthermore, the simulation model was adapted for simulations of two other ALPIDE-based detector projects; the Proton CT (pCT) project at University of Bergen (UiB), a Digital Tracking Calorimeter (DTC) used for dose planning of particle therapy in cancer treatment; and the planned Forward Calorimeter (FoCal) for ALICE, where there will be two layers of pixel sensors among the 18 layers of Si-W calorimeter pads in the electromagnetic part of the detector (FoCal-E). Since the size of a calorimeter pad is relatively large, around 1 cm², the fine grained pixels of the ALPIDE (29.24 µm × 26.88 µm) will help distinguish between multiple showers and improve the overall spatial resolution of the detector. The simulations helped prove the feasibility of the ALPIDE for this detector, from a readout perspective, and FoCal was later approved by the LHCC committee at CERN.Doktorgradsavhandlin

UPAYA MENINGKATKAN MOTIVASI BELAJAR SISWA MELALUI MEDIA GAME EDUCATION DALAM PEMBELAJARAN IPS DI MTs HASBUR RACHMAN ALIF DESA LENGKONG WETAN KABUPATEN MAJALENGKA

ASEP SAMSUL MA'ARIF : Berdasarkan Observasiawal di kelas VII MTs Hasbur Rachman Alif terlihat proses pembelajaran IPS masih menggunakan media spidol dan papan tulis. Sehingga banyak siswa yang kurang memperhatikan guru pada saat proses pembelajaran., Hal ini berakibat pada kejenuhan dan kebosanan yang berdampak pada hasil belajar siswa yang kurang dari KKM yang diterapkan di MTs Hasbur Rachman Alif yakni 70. Tujuan penelitian ini untuk mengetahui bagaimana penerapan pembelajaran dengan menggunakan media Game Education pada mata pelajaran IPS Terpadu, aktivitas siswa dan kinerja guru dengan pembelajaran dengan menggunakan media Game Education, dan mengetahui motivasi belajar siswa sebelum dan setelah diterapkannya pembelajaran dengan menggunakan media Game education pada mata pelajaran IPS Terpadu di MTs Hasbur Rachman Alif. Pembelajaran dengan menggunakan media Game Education menekankan motivasi siswa untuk berpikir kritis dan menuangkan. Hal ini memudahkan siswa untuk mengakses materi IPS yang banyak dimanapun, serta mempemudah daya ingat siswa tentang apayatgtelah didapatkan selama proses pembelajaran. Penelitian ini menggunakan Penelitian Tindakan Kelas (pTK) yang dilaksanakan selama tiga siklus. Teknik Pengumpulan data menggunakan observasi, tes, dan dokumentasi. Subjek penelitian ini adalah siswa kelas VII MTs Hasbur Rachman Alif sebanyak 31 siswa yang terdiri dari 18 siswa laki-laki dan 13 siswa perempuan. Pembelajaran dengan menggunakan media Game Education dapat meningkatkan motivasi belajar siswa hal ini terlihat dari hasil tes yang telah dilakukan selama tiga siklus, dimana pada pratindakan (pretes) nilai sebesar 65,25 dan ketuntasan belajar 25 yo, siklus I nilai rata-rata sebesar 76,75 dan ketuntasan_ belajar siswa sebesar 65,5%o siklus II nilai rata-rata siswa 85,75 dan nilai ketuntasan belajar sebesar 90% siklus III dengan nilai rata-rata 92,25 dan ketuntasan belajar mengalami peningkatanya itu 97,5yo. Dengan demikian dapat disimpulkan bahwa pembelajaran dengan menggunakan media Game Education merupakan salah satu upaya untuk meningkatkan hasil belajar siswa pada mata pelajaran IPS Terpadu di MTs Hasbur Rachman Alif. Kata Kunci: Game Education, MotivasiBelajar, PTK

Production of charged pions, kaons, and (anti-)protons in Pb-Pb and inelastic pp collisions at √sNN=5.02 TeV

Midrapidity production of π±, K±, and (¯p)p measured by the ALICE experiment at the CERN Large Hadron Collider, in Pb-Pb and inelastic pp collisions at √sNN=5.02 TeV, is presented. The invariant yields are measured over a wide transverse momentum (pT) range from hundreds of MeV/c up to 20 GeV/c. The results in Pb-Pb collisions are presented as a function of the collision centrality, in the range 0–90%. The comparison of the pT-integrated particle ratios, i.e., proton-to-pion (p/π) and kaon-to-pion (K/π) ratios, with similar measurements in Pb-Pb collisions at √sNN=2.76 TeV show no significant energy dependence. Blast-wave fits of the pT spectra indicate that in the most central collisions radial flow is slightly larger at 5.02 TeV with respect to 2.76 TeV. Particle ratios (p/π, K/π) as a function of pT show pronounced maxima at pT≈3 GeV/c in central Pb-Pb collisions. At high pT, particle ratios at 5.02 TeV are similar to those measured in pp collisions at the same energy and in Pb-Pb collisions at √sNN=2.76 TeV. Using the pp reference spectra measured at the same collision energy of 5.02 TeV, the nuclear modification factors for the different particle species are derived. Within uncertainties, the nuclear modification factor is particle species independent for high pT and compatible with measurements at √sNN=2.76 TeV. The results are compared to state-of-the-art model calculations, which are found to describe the observed trends satisfactorily.publishedVersio

J/ψ elliptic and triangular flow in Pb-Pb collisions at √sNN = 5.02 TeV

The inclusive J/ψ elliptic (v2) and triangular (v3) flow coefficients measured at forward rapidity (2.5 < y < 4) and the v2 measured at midrapidity (|y| < 0.9) in Pb-Pb collisions at sNN−−−√ = 5.02 TeV using the ALICE detector at the LHC are reported. The entire Pb-Pb data sample collected during Run 2 is employed, amounting to an integrated luminosity of 750 μb−1 at forward rapidity and 93 μb−1 at midrapidity. The results are obtained using the scalar product method and are reported as a function of transverse momentum pT and collision centrality. At midrapidity, the J/ψ v2 is in agreement with the forward rapidity measurement. The centrality averaged results indicate a positive J/ψ v3 with a significance of more than 5σ at forward rapidity in the pT range 2 < pT < 5 GeV/c. The forward rapidity v2, v3, and v3/v2 results at low and intermediate pT (pT ≲ 8 GeV/c) exhibit a mass hierarchy when compared to pions and D mesons, while converging into a species-independent curve at higher pT. At low and intermediate pT, the results could be interpreted in terms of a later thermalization of charm quarks compared to light quarks, while at high pT, path-length dependent effects seem to dominate. The J/ψ v2 measurements are further compared to a microscopic transport model calculation. Using a simplified extension of the quark scaling approach involving both light and charm quark flow components, it is shown that the D-meson vn measurements can be described based on those for charged pions and J/ψ flow.publishedVersio

Spin alignment measurements using vector mesons with ALICE detector at the LHC

We present new measurements related to spin alignment of K*0 vector mesons at mid-rapidity for Pb–Pb collisions at √sNN = 2.76 and 5.02 TeV. The spin alignment measurements are carried out with respect to production plane and 2nd order event plane. At low pT the spin density matrix element ρ00 for K*0 is found to have values slightly below 1/3, while it is consistent with 1/3, i.e. no spin alignment, at high pT. Similar values of ρ00 are observed with respect to both production plane and event plane. Within statistical and systematic uncertainties, ρ00 values are also found to be independent of √sNN. ρ00 also shows centrality dependence with maximum deviation from 1/3 for mid-central collisions with respect to both the kinematic planes. The measurements for K*0 in pp collisions at √s = 13 TeV and for K0S (a spin 0 hadron) in 20-40% central Pb–Pb collisions at √sNN = 2.76 TeV are consistent with no spin alignment.publishedVersio

Mid-Staffordshire:a case study of failed governance and leadership?

Hadronic resonances are unique tools to investigate the interplay of re-scattering and regeneration effects during the hadronization phase in heavy-ion collisions. Measurements in small collision systems provide a necessary baseline for heavy-ion data, help to tune pQCD inspired event generators and give insight into the search for the onset of collective effects. As the ϕ meson has a longer lifetime compared to other resonances, it is expected that its production would be much less affected by regeneration and re-scattering processes. We report on measurements of ϕ meson production in minimum bias pp collisions at different beam energies and as a function of charged particle multiplicity with the ALICE detector at the LHC. The results include the transverse momentum (pT) distributions of ϕ as well as the particle yield ratios. Finally, we have also studied the ϕ effective strangeness content by comparing our results to theoretical calculations

Measurement of electrons from heavy-flavour hadron decays as a function of multiplicity in p-Pb collisions at √sNN = 5.02 TeV

The multiplicity dependence of electron production from heavy-flavour hadron decays as a function of transverse momentum was measured in p-Pb collisions at √sNN = 5.02 TeV using the ALICE detector at the LHC. The measurement was performed in the centre-of-mass rapidity interval −1.07 < ycms< 0.14 and transverse momentum interval 2 < pT< 16 GeV/c. The multiplicity dependence of the production of electrons from heavy-flavour hadron decays was studied by comparing the pT spectra measured for different multiplicity classes with those measured in pp collisions (QpPb) and in peripheral p-Pb collisions (Qcp). The QpPb results obtained are consistent with unity within uncertainties in the measured pT interval and event classes. This indicates that heavy-flavour decay electron production is consistent with binary scaling and independent of the geometry of the collision system. Additionally, the results suggest that cold nuclear matter effects are negligible within uncertainties, in the production of heavy-flavour decay electrons at midrapidity in p-Pb collisions.publishedVersio

The new Inner Tracking System of the ALICE experiment

The ALICE experiment will undergo a major upgrade during the next LHC Long Shutdown scheduled in 2019&ndash;20 that will enable a detailed study of the properties of the QGP, exploiting the increased Pb-Pb luminosity expected during Run 3 and Run 4. The replacement of the existing Inner Tracking System with a completely new ultra-light, high-resolution detector is one of the cornerstones within this upgrade program. The main motivation of the ITS upgrade is to provide ALICE with an improved tracking capability and impact parameter resolution at very low transverse momentum, as well as to enable a substantial increase of the readout rate. The new ITS will consist of seven layers of innovative Monolithic Active Pixel Sensors with the innermost layer sitting at only 23 mm from the interaction point. This talk will focus on the design and the physics performance of the new ITS, as well as the technology choices adopted. The status of the project and the results from the prototypes characterization will also be presented.publishedVersio

J/ψ production as a function of charged-particle multiplicity in p-Pb collisions at √sNN = 8.16 TeV

Inclusive J/ψ yields and average transverse momenta in p-Pb collisions at a center-of-mass energy per nucleon pair sNN−−−√ = 8.16 TeV are measured as a function of the charged-particle pseudorapidity density with ALICE. The J/ψ mesons are reconstructed at forward (2.03 < ycms < 3.53) and backward (−4.46 < ycms < −2.96) center-of-mass rapidity in their dimuon decay channel while the charged-particle pseudorapidity density is measured around midrapidity. The J/ψ yields at forward and backward rapidity normalized to their respective average values increase with the normalized charged-particle pseudorapidity density, the former showing a weaker increase than the latter. The normalized average transverse momenta at forward and backward rapidity manifest a steady increase from low to high charged-particle pseudorapidity density with a saturation beyond the average value.publishedVersio

Study of J/ψ azimuthal anisotropy at forward rapidity in Pb-Pb collisions at √sNN=5.02 TeV

The second (v2) and third (v3) flow harmonic coefficients of J/ψ mesons are measured at forward rapidity (2.5 < y < 4.0) in Pb-Pb collisions at √ sNN = 5.02 TeV with the ALICE detector at the LHC. Results are obtained with the scalar product method and reported as a function of transverse momentum, pT, for various collision centralities. A positive value of J/ψ v3 is observed with 3.7σ significance. The measurements, compared to those of prompt D0 mesons and charged particles at mid-rapidity, indicate an ordering with vn(J/ψ) < vn(D0 ) < vn(h±) (n = 2, 3) at low and intermediate pT up to 6 GeV/c and a convergence with v2(J/ψ) ≈ v2(D0 ) ≈ v2(h±) at high pT above 6–8 GeV/c. In semicentral collisions (5–40% and 10–50% centrality intervals) at intermediate pT between 2 and 6 GeV/c, the ratio v3/v2 of J/ψ mesons is found to be significantly lower (4.6σ) with respect to that of charged particles. In addition, the comparison to the prompt D0 -meson ratio in the same pT interval suggests an ordering similar to that of the v2 and v3 coefficients. The J/ψ v2 coefficient is further studied using the Event Shape Engineering technique. The obtained results are found to be compatible with the expected variations of the eccentricity of the initial-state geometry.publishedVersio