Introductin of the research team
The researchers involved in the project are lecturers at the Department of Electrical Engineering, Experimental and Solid State Physics, Institute of Physics, Faculty of Science and Technology, Department of University of Debrecen. Their research topics range from detection problems in high-energy physics to the development of sensors used in everyday life. Using first physical principles, we are developing new solutions for sensitive detection of photons emitted in various energetic physical processes. Our knowledge of materials helps us to select right materials, to design and build the associated electronics and to draw important conclusions from the physical process under investigation.
The mission of the Space Physics Research Group in the project is to research, develop and implement small, autonomous, self-communicating sensing units capable of detecting high-energy ionizing radiation. The sensing units will be able to sense the presence of radiation and issue an alarm after processing the data. By spreading several sensors over one area, the spatial distribution of the radiation can be measured, creating a communication network between the sensor units and transmitting the measured data to the center. Small-scale devices, used even in outer space, are capable of mapping and continuously monitoring the radiation field.
It is a special task to design, build, and certify electronic equipment operating in space conditions significantly different from those of Earth. Not only extreme temperatures, mechanical stress, but also the particle irradiation that occur in outer space affect the operation of semiconductor based devices. The radiation hardness of the electronic components and circuits shall be tested in prototype and production phase. In collaboration with Institute for Nuclear Research (ATOMKI), we investigate the effects of high intensity irradiation on electronic units during operation. Our aim is to qualify and test the radiation hardness of electronic devices, components and materials intended to be applied in space.
The actual R&D activities and tasks of the research group are the following:
The principal goal of relativistic heavy ion physics is to study the genesis of the Universe, by recreating in the lab the so called quark-gluon plasma (QGP), the elusive state of matter in which the entire Universe existed a few millionth of a second after the Big Bang, and to study the properties of the QGP. Why is this important? Because our entire world evolved, over billions of years, governed by strict laws of physics, from this primordial QGP. Just as one cannot fully understand a living organism without knowing how it originated, many secrets of today's Universe will elude us unless we understand its origin, the QGP. While the QGP is governed by the so called strong interaction, the QCD equations cannot be solved in the most relevant, "soft" region. The way out is to collect empirical evidence in order to narrow down the range of possible scenarios. Since rigorous calculations are not feasible, theorists create intuitive "phenomenological" models of the QGP and the laws of its dynamics, and by confronting them with experimental observations gradually improve upon them. Photons, once created, come out freely, they "shine through" the QGP, not unlike X-rays through the human body. While very hard to measure, they offer a unique, unobstructed view of what's happening inside the QGP. This proposal focuses on searching for photons, analyzing data already available and also, building a next generation photon detector for a future experiment.
One possible social utility is the knowledge we gained at high energy physics can be adapted to a more precise medical imaging due to the SiPM based TOFPET.
In this research project we shall focus on improving direct-photon measurements in high-energy heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) in Brookhaven National Laboratory. Our research plan has two main directions: analysis of data already taken by the PHENIX detector at RHIC and publishing the results; participating in the design, simulations and detector tests of the calorimeters in a next generation experiment, super PHENIX (sPHENIX).
In sPHENIX both the electromagnetic and the hadronic calorimeter will utilize plastic scintillators that are read out with silicon photomultipier (SiPM) sensors, altogether more than 120 thousand devices, subject to moderate radiation load. These devices have to be characterized and tested, in order to allow them to be matched in groups before mounting them on the calorimeter modules We started the development -together with the National Instruments Hungary- an adequately sized, semi-automated test equipment, and provide the necessary control, data acquisition and processing software, which makes it possible to complete the tests within 1.5 years. We delivered the prototype test equipment to University of Michigan, in the next months we will set it up, train future operators, and provide expert help during its operation. We co-operate with an interested group at University of Michigan, Michigan, USA, who currently lack the experience with SiPMs but have sufficient human resources (students and a postdoc. Two early prototypes were already created by the Debrecen group. The first device (2016 May) was a proof of concept, it showed, that we can read out the signal of a single SiPM at the single pixel level, the SiPM was replaceable. The second device can test 4 SiPMs simultaneously and three independent methods were developed to measure the breakdown voltage. The final device should be able to test about 50-100 SiPMs in couple of hours.
Silicon photomultipliers are known to be sensitive to various types of radiation, in particular, fast neutrons with energies on the order of a few MeV. It is expected that the neutron fluence in sPHENIX will cause significant effects in the SiPMs with time and may have an effect on their performance. Taking advantage of the existing facilities and available expertise at ATOMKI we will expose SiPM's to different types of radiation, including fast neutrons, and characterize them before, during and after irradiation.
In the prototyping and construction phase of sPHENIX there will be regular beam tests of detector components at Fermilab. We intend to participate in some of them, to gain experience with sPHENIX hardware, and get involved in FPGA programming of the readout. Also, the beam test results will be an important input to the verification of the sPHENIX simulations.