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11. 7. 2019. Characterization of semiconductor detectors using laser Transient Current Technique

Speaker: Dr. Matti Kalliokoski, Ruđer Bošković Institute
Location: Ion Beam Facility, Van De Graaf lecture room, RBI
Time: 11. 7. 2019 at 14:00.

Transient Current Technique (TCT) is one of the principal tools for studying solid state particle detectors. In a TCT-setup, the signal current of the charge carriers is directly amplified and read out, and thus their movement can be analyzed with high time resolution. By combining the signal output with position information, locations of defects and other non-uniformities can be mapped, and their effect to the charge collection efficiency can be studied. In this talk I present results of scans with the laser-TCT setup at the Ruđer Bošković Institute in characterizing various silicon and CdTe detectors.

Red laser TCT measurement of CCE of an area of a CdTe detector
TCT measurement of CCE of an area of a CdTe detector.

8. 7. 2019. Particle detectors for high energy ion beam applications

Speaker: Prof. Kamiya Tomihiro, University of Gunma
Location: Lecture hall Wing I, RBI
Time: 8. 7. 2019 at 12:00.

5. 6. 2019. Testing for Single Event Effects due to ionizing particles in microelectronics VLSI circuitry

Speaker: Dr. Fco. Rogelio Palomo Pinto, University of Seville
Location: Ion Beam Facility, Van De Graaf lecture room, RBI
Time: 5. 6. 2019 at 14:00.

The seminar will discuss how to test for Single Event Effects due to ionizing particles in microelectronics VLSI circuitry. The high density of circuits, the small size and the diversity of effects justify the use of nuclear microscopy techniques for SEE testing. By simulation we can assess the chip vulnerability to SEE. A microprobe end station is the experimental perfect match to generate physical sensitivity maps for the chip due to the pinpointing beam accuracy. The microbeam technique for SEE sensitivity map was developed by the author in the Seville microprobe facility for a less demanding integration scale (500nm). The RBI microprobe has better resolution, so it is the perfect tool for nanometric technologies such as the one present at the 65nm (2x2 mm2 chip, target blocks smaller than 20x20 um2).


7. 5. 2019. Building a new pixel detector for the CMS experiment at the High Luminosity LHC

Speaker: Dr. Devdatta Majumder, University of Kansas
Location: Ion Beam Facility, Van De Graaf lecture room, RBI
Time: 7. 5. 2019 at 11:00.

The innermost component of the CMS detector is a pixel tracker. It is used to identify proton-proton collision interaction points and reconstruct bottom and charm hadron decays. Hence this detector is important in identifying jets from heavy flavour quark fragmentation. The current pixel detector will remain operational until about 2023. The LHC will henceforth be upgraded to collide proton beams at an intensity about five times the present value. A new pixel detector is being designed (Phase-2 upgrade) to cope with the high radiation and collision rates at the high luminosity LHC. In this talk, I will discuss the ongoing research and development activities on Phase-2 pixel detector, focusing on those conducted at CERN by the various research groups.


3. 5. 2019. Semiconductor detector research and development at the Helsinki Institute of Physics (HIP)

Speaker: Dr. Eija Tuominen, Helsinki Institute of Physics
Location: Wing 1 lecture room (Supek), RBI
Time: 3. 5. 2019 at 11:00.

The Helsinki Institute of Physics (HIP) is a physics research institute that is operated jointly by the University of Helsinki, Aalto University, the University of Jyväskylä, the Lappeenranta-Lahti University of Technology, and the Tampere University. HIP Detector Laboratory is a national infrastructure supporting Finnish experimental research on detector development activities. For decades the laboratory has provided premises, equipment and know-how for research projects developing semiconductor radiation detectors for large international particle and nuclear physics experiments, for medical imaging and for nuclear safety applications.

One of our long-term activities has been the development of radiation hard silicon detectors for future very high luminosity collider experiments, especially for the upgrade of CERN Compact Muon Solenoid (CMS) particle tracking detector entering into High Luminosity Large Hadron Collider (HL-LHC) era. Our approach has been the implementation of strip and pixel detectors made of oxygen rich Magnetic Czochralski silicon (MCz-Si) wafers produced in large quantities by Okmetic Ltd located in Vantaa, Finland. Detector fabrication has been carried out at the semiconductor processing clean room premises of our strategic partner Micronova Nanofabrication Centre.

Furthermore, the HIP Detector Laboratory participated in the production and quality assurance (QA) of the Phase I upgrade of the innermost pixel detector system of the CMS Tracker experiment. A bare CMS Tracker pixel module consists of one silicon pixel detector and 16 read-out CMOS circuits (ROC) that are flip-chip (FC) bonded to the pixel detector. Altogether, one pixel detector module has about 67 000 pixels. By the end of 2016, we tested and delivered about 20% of the modules needed in the CMS Tracker Phase I pixel detector upgrade. The required quality level was successfully reached, and the average bad interconnections in the bare pixel modules were less than 0.1%.

Further upgrades of CMS Tracker pixel sensors and associated read-out electronics are needed. Thus, our on-going activity is to provide new pixel detector modules for CMS Tracker experiment in similar quantities as previously during the Phase I Upgrade. This project is carried out in collaboration with Paul Scherrer Institute (PSI), Ruđer Bošković Institute (RBI) and company Advacam Oy, operating in Micronova clean room premises.


26. 4. 2019. The Higgs boson and Heavy Quarks at CMS - with a focus on experimental aspects

Speaker: Prof. Dr. Lea Caminada, Paul Scherrer Institute and University of Zurich
Location: Wing 3 lecture room, RBI
Time: 26. 4. 2019 at 15:00.

The discovery of the Higgs boson in 2012 opened a new era of extrapolation in high-energy physics driven by the desire to understand the properties of this new state. A crucial aspect is the measurement of the couplings of the Higgs boson with other particles in order to determine whether the Higgs boson indeed belongs to the Standard Model or if possible deviations indicate new physics effects. I present the latest results of studies of the Higgs boson couplings to top and bottom quarks in the search for the Higgs bosons decaying into b quarks and produced in association with top quark pairs. Furthermore, I discuss future prospects for measurements of Higgs bosons and heavy quarks with the high-luminosity data to be collected at the LHC over the coming years.

Experimentally, the tagging of heavy flavor quarks is one of the main challenges in these searches. In particular the measurements rely on an excellent tracking detector with the ability to precisely reconstruct primary and secondary vertices from the decay of heavy flavor quarks. The CMS experiment features a silicon pixel detector that meets these demands by providing high resolution data in the region closest to the interaction point. Since the pixel detector is operated in a particularly harsh environment characterized by a high track multiplicity and heavy irradiation, the design of the detector is very demanding. In order to cope with the higher instantaneous luminosities that have been achieved by the LHC after the first long shutdown of the accelerator the original CMS pixel detector has been replaced with an upgraded pixel system at the beginning of the year 2017. I will review the design and construction of the upgrade pixel detector and discuss its performance during the first years of operation.

24. 1. 2019. The MoEDAL Experiment at the LHC - Searching for Physics Beyond the Standard Model

Speaker: Dr. Matti Kalliokoski, Ruđer Bošković Institute
Location: Wing 1 lecture room (Supek), RBI
Participants: RBI and project staff

MoEDAL is a pioneering experiment designed to search for highly ionizing messengers of new physics such as magnetic monopoles or massive (pseudo-)stable charged particles, that are predicted to exist in a plethora of models beyond the Standard Model. It started data taking at the LHC at a centre-of-mass energy of 13 TeV, in 2015. MoEDAL’s ground breaking physics program defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as: are there extra dimensions or new symmetries; what is the mechanism for the generation of mass; does magnetic charge exist; and what is the nature of dark matter. MoEDAL’s purpose is to meet such far-reaching challenges at the frontier of the field.

The innovative MoEDAL detector employs unconventional methodologies tuned to the prospect of discovery physics. The largely passive MoEDAL detector, deployed at Point 8 on the LHC ring, has a dual nature. First, it acts like a giant camera, comprised of nuclear track detectors – analyzed offline by ultrafast scanning microscopes with various pattern recognition and machine learning methods. Second, it is uniquely able to trap the particle messengers of physics beyond the Standard Model for further study. MoEDAL’s radiation environment is monitored by a state-of-the-art real-time TimePix pixel detector array.

I will present an overview of the MoEDAL detector, including the planned upgrades with MAPP and MALL sub-detectors, as well as MoEDAL’s physics program. I will also show some highlights of the physics results on Magnetic Monopole production, that are the world’s best for Monopoles with multiple magnetic charge.

MoEDAL Detector at the LHC
MoEDAL detector at the LHC.

24.-25. 10. 2018. Workshop on silicon photomultipliers and on dosimetry techniques in radiotherapy

Speakers: Prof. Massimo Caccia, Dr. Romualdo Santoro, and Samuela Lomazzi, Università degli Studi dell’Insubria
Location: On 24.10. Wing 1 lecture room (Supek) at 10 am, and on 25.10. Wing 3 lecture room at 3 pm.

Wed 24.10.
Introduction to Silicon Photomultipliers, M. Caccia
Massimo Caccia giving an introductory lecture at the RBI.
AbstractPart 1Part 2

Demonstration of SiPM start kit by CAEN s.p.a.
SP5600AN Educational Kit - Premium Version at CAEN web page

Thu 25.10.
Fibre sensors for in vivo dosimetry during radiotherapy, S. Lomazzi
Samuela Lomazzi giving presentation at the RBI.

Silicon Photomultiplier based dual-readout fibre calorimeter: firsts results and the pathway beyond the proof-of-concept, R. Santoro
Romualdo Santoro giving presentation at the RBI.

4. 9. 2018. Development of Novel Semiconductor Detectors In Xiangtan University

Speaker: Prof. Zheng Li, Xiangtan Technical University (XTU)
Location: Wing 1 lecture room (Supek), RBI
Participants: RBI and project staff

Development of novel large area Si drift detectors (SDD) and 3D-Trench-Electrode detectors have been carried out in Xiangtan University. These detectors are applied for X-ray and particle detection in the field of high energy physics, photon science, and space applications. Large area (600 mm2 and 314 mm2) SDD detectors have simulated, designed in Xiangtan University, and been fabricated in its new Class-100 cleanroom high resistivity Si detector processing facility. Simulations on the the new 3D-Trench-Electrode detectors have been carried out, and results have shown great radiation hardness as compared to convention 2D planar detectors. Leakage current and capacitance measurements have shown good results. Laser scan tests on the new 3D-Trench-Electrode detectors have shown good sensitivity and good pixel separation.

RBI-XTU-HIP X-ray drift detector mask design
RBI-XTU drift detector mask design.


27. 2. 2018. The basics of Geant4 and possible applications

Speaker: Dr. Matti Kalliokoski, Ruđer Bošković Institute
Location: Van de Graaff seminar room, RBI
Participants: RBI and project staff

Geant4 is a C++ based simulation toolkit that is used widely in design and analysis of high energy physics experiments, in space and radiation applications, and in medical physics. It can be used to simulate the passage of particles through matter. Geant4 physics processes describe electromagnetic and nuclear interactions of particles with matter, at energies from eV to TeV. In this seminar presentation I will briefly go through the basics of Geant4 toolkit, and show some applications from various fields from accelerator physics to space environment.

Planetary gearbox under neutron irradiation.

Geant4 simulation of a gearbox irradiated with neutrons.

26. 1. 2017. Alpha-screening of contaminated curved objects with flexible silicon

Speaker: Dr. Christian Schuster, University of York
Location: RBI
Participants: RBI and project staff

The detection of alpha radiation in the field can be challenging due to their short range, which is typically only some centimeters in air. This problem is exacerbated inside contaminated pipeline systems in the nuclear industry: there is currently no low cost solution available for measuring low levels of alpha-contamination, like Pu-239, inside pipes, because cutting a long pipework into segments is expensive and, therefore, incompatible for the inspection.

While previous methods mainly focused on indirect techniques, I will propose a novel approach based on a flexible sheet of 50 µm thin crystalline silicon. Following established fabrication steps of pn-junction diodes, we observe a very clear response to 5 MeV alpha-particles using a bespoke amplifier circuit. As a flexible detector offers 360-degree equidistant surface coverage and is able to adapt to the curvature of a given pipeline, I will show that our prototype device stands out as a low-cost and efficient solution for nuclear decommissioning.

Even if the sensor is aimed at the specific problem of assessing radioactive contamination in narrow pipe work, it can generally be adapted to a curved surface, such as barrels for contaminated waste. In my talk, I would like to discuss how it can also address requirements of nuclear and particle physics experiments.

Crystalline silicon wafers become flexible at ca. 70 µm thickness.

Crystalline silicon wafers become flexible at ca. 70 µm thickness. Accordingly, they can be bent to be used for screening the inner surface of a 2” diameter pipe for alpha-contamination and be mounted on an elastic inspection gauge.