News

eRosita pnCCDs make the X-ray sky visible

14.02.2024

Data from the first sky survey by the imaging X-ray telescope eRosita has now been released. The result: sources of around 710,000 supermassive black holes in distant galaxies, over 180,000 active stars in our own Milky Way up to 12,000 galaxy clusters and a small number of other exotic sources such as X-ray emitting binary stars, supernova remnants, pulsars and other objects. The basis for the novel detector system is the semiconductor laboratory's pnCCD technology.

The pnCCD detector enables precise spectroscopy of X-rays and imaging with high time resolution. It is based on the successful XMM-Newton pnCCD detector concept, but has been further improved in terms of design and technology. The pnCDDs have been redesigned and manufactured using innovative technology. State-of-the-art developments such as the self-aligning CCD register technology were used. The X-Ray Multi-Mirror (XMM-Newton) satellite was launched by the European Space Agency (ESA) in 1999. In particular, an image storage area was added to the imaging area to allow simultaneous imaging and readout in separate CCD areas. The overall pnCCD chip thickness of 450 μm is uniformly sensitive to X-rays from very low to very high energies. The X-ray photon detection efficiency is at least 90 % in the energy band from 0.3 keV to 10 keV. The image storage mode enables very high frame rates of up to 200 X-ray images per second without image smearing.

The eRASS1 observations (eROSITA All-Sky Survey Catalog) with the eROSITA telescope were carried out from December 12, 2019 to June 11, 2020. In the most sensitive energy range of the eROSITA detectors (0.2-2 keV), the telescope detected 170 million X-ray photons for which the cameras can accurately measure the incoming energy and arrival time.

A further development of the HLL's eRosita-pnCCDs has recently left Earth. The Einstein Probe spacecraft of the Chinese Academy of Sciences (CAS) lifted off on January 9, 2024 with a Chang Zheng 2C rocket from the Xichang Satellite Launch Center in China.

After the launch, the Einstein probe reached its orbit at an altitude of around 600 kilometers. The probe orbits the Earth every 96 minutes with an orbital inclination of 29 degrees and is able to observe almost the entire night sky in just three orbits.

pnCCDs, which are developed and produced at the Max Planck Semiconductor Laboratory, are sensors for light and particle detection. They are used in satellites for X-ray astronomy, for which new semiconductor sensors are required. They enable the detection threshold for soft X-rays. pnCCDs can be tailored to the needs of X-ray spectroscopy and X-ray photon counting. In them, the storage capacitors are constructed with pn junctions instead of MOS structures. This eliminates the sensitive silicon-silicon dioxide interface, making a pn-CCD intrinsically more radiation-hard. Over the past three decades, HLL has developed and produced many versions of pn-CCDs, mainly for applications in satellite-based X-ray spectroscopy cameras (XMM-Newton, eRosita, Einstein Probe) and materials science (CAMP, LAMP). The design and technology of pnCCDs is constantly being further developed. Most recently, following self-aligning CCD register technology, new low-impedance register bus connections with polysilicon have been used, which enable a much faster charge transfer from the sensor to the image storage area.

Made in Germany: World’s thinnest pixel vertex detector installed in Japan

08.08.2023

The pixel vertex detector, which is about the size of a soda can and is the innermost sub-detector of the international experiment Belle II, has been successfully installed at its final location at the SuperKEKB electron–positron collider at the KEK laboratory in Japan. The device, which is designed to detect the signals of certain particle decays that could shed light on the origin of the observed imbalance of matter and antimatter in the universe, has ventured a long way over a long time from its production site in Munich to its final destination in Japan.

original
original
original
original

The Pixel Vertex Detector (PXD) wraps around the beam pipe of the SuperKEKB accelerator and sits only 1.4 cm away from the collision point in the Belle II detector. This positioning enables the detector to reconstruct the decay point of short-lived particles from the collisions as accurately as possible. The PXD consists of 20 strips of silicon wafers 75 micrometres thick – that’s the width of a human hair – arranged in two concentric cylindrical layers. The novel detector, based on DEPFET technology developed at the Max Planck Semiconductor Laboratory in Munich, is designed to provide up to 50,000 high-resolution images per second of the decays of B mesons, which are abundantly produced in the electron–positron collisions at SuperKEKB.

“The B-meson system is an ideal laboratory to study one of the most fundamental symmetries in nature: The violation of charge parity symmetry is one of three conditions that must be fulfilled to explain why today's universe consists almost entirely of matter,” says DESY scientist Carsten Niebuhr, who is the PXD project leader. “The high precision of the Belle II detector combined with the unprecedented statistics of the electron-position collisions at SuperKEKB provide unique opportunities to study CP violation and other interesting phenomena in much greater detail.”

However, the B meson decay products have relatively low energy and are easily disturbed as they pass through the detector material. Therefore, for Belle II, it was necessary that the first detector elements be as light as possible, making the PXD very fragile and its handling extremely delicate. “We are very proud that the Munich groups contributed essential parts of the detector concept and development,” says Hans-Günther Moser, head of the Belle II group at MPP. “With the help of DEPFET technology, highly complex and ultrasensitive sensors are used in the Belle II experiment, which are also used in satellite experiments. This technology underlines the Semiconductor Laboratory's globally unique expertise in radiation detectors.”

The detector flies business class

An earlier but incomplete version of the PXD was already installed at Belle II in 2018, but this new addition will be able to handle the higher-luminosity that SuperKEKB is expected to deliver in the coming years. In order to get the detector to Japan, it first needed to be transported by road from its assembly site at MPP in Munich to DESY for critical performance tests and optimisation of detector parameters. “Every bump in the road almost gave me a heart attack,” says PXD commissioning leader Arthur Bolz, who, together with his colleagues, had to overcome numerous unexpected problems that arose when operating a complete PXD half-shell for the first time.

Following successful testing, the reassembled detector once more needed to take a trip – this time thousands of kilometres east to Japan. The air travel presented new challenges – unexpected turbulence and improper storage during transit could easily have broken one of the sensitive silicon strands. To combat this, the team packed the detector to minimise vibrations, and took it on a business-class flight to give it as much space as possible while allowing the team to “babysit” it at all times.

PXD2 starts working at the beginning of 2024

“The commissioning and installation of the PXD required not only the preparation and insertion of the very fragile detector itself, but also the commissioning of the associated complex service systems, consisting of customised power supplies and readout electronics. In particular, the very limited space within the detector volume made this an extremely challenging task, which required close cooperation with several other detector groups in order to avoid potential conflicts,” says DESY scientist Fabian Becherer, who spent several months at KEK as a member of the PXD commissioning team.

Now installed, the detector is expected to begin data collection early in 2024. “It has been a challenging several year long journey to arrive here. I am proud of the entire PXD team for making it possible and am excited to be present for this big moment,” says Botho Paschen, a researcher at the University of Bonn who is the technical coordinator of the PXD project. “Finally taking physics data with the full-fledged detector in a few months is a thrilling perspective.”

Involved in the PXD’s design and construction have been DESY, the Max Planck Institute for Physics in Munich, the Semiconductor Laboratory of the Max Planck Society, the University of Bonn, the University of Gießen, the University of Göttingen, the University of Munich, the Technical University of Munich, the University of Mainz, and the Karlsruhe Institute of Technology. Other institutes in Spain and Czechia also contributed.

Laci Andricek from the Semiconductor Laboratory in Munich and co-developer of the PXD sums up: “It is both exciting and relieving to be able to witness how the PXD, from the conception of the detector, to the development and production of the sensors and modules at the Semiconductor Laboratory of the Max Planck Society, to the integration at MPP and DESY, finally arrives at its destination.”

The German research groups in the Belle II experiment are funded by the following institutions and programmes:

  • Alexander von Humboldt Foundation
  • Federal Ministry of Education and Research (BMBF)
  • German Research Foundation (DFG), in particular within the framework of the Excellence Strategy of the German Federal Government and the Federal States:
    • "ORIGINS": EXC-2094 - 390783311
    • "Quantum Universe": EXC-2121 - 390833306
  • European Research Council - European Union's Horizon 2020 - grant agreement No 822070
  • Helmholtz Association
  • Max Planck Society

Together for science: Exhibition stand for research into the universe and matter inspires visitors at the Hanover Fair

11.05.2023

As part of its participation in the research projects "ATLAS", carried out at the LHC (Large Hadron Collider) at CERN, and "BELLE II", which takes place at the SuperKEKB in Tsukuba, Japan, the Semiconductor Laboratory of the Max Planck Society was represented at the booth "ERUM - Exploring the Universe and Matter" at this year's Hannover Messe. From April 17 to 20, more than 4,000 exhibitors from over 70 countries presented their latest innovations, products and services at Germany's largest industrial fair.

For a whole week, visitors to the joint stand were able to gain exciting insights into the day-to-day work of German scientists and learn first-hand what it means to explore the universe and matter, how the particle detectors at the Large Hadron Collider and SuperKEKB are set up, and what methods are subsequently used to analyze the data collected. A special highlight and real crowd puller was a microscope with which a fragment of a DEPFET pixel detector, produced by the Semiconductor Laboratory of the Max Planck Society, could be admired in close-up.

The positive response of visitors* to the joint booth clearly showed that industrial trade fairs are also a suitable venue for projects from research and promote exchange between science and industry.

About the exhibitors:

With the framework program "Exploration of Universe and Matter" (ErUM), the Federal Ministry of Education and Research in Germany promotes excellent basic scientific research at research infrastructures. In individually organized research foci (ErUM-FSPs), scientists* from German universities and non-university research institutions are networked to jointly answer major questions of humanity.

The ErUM research foci at the LHC

At the Large Hadron Collider (LHC), the world's most powerful particle accelerator at the CERN research center near Geneva, scientists are working together internationally to investigate the elementary building blocks of matter and the fundamental laws of nature in the universe. More than 1300 scientists from Germany are significantly involved in these investigations. Analogous to the large-scale experiments at the LHC, the German working groups have joined together to form four research foci (ErUM-FSPs): ALICE, ATLAS, CMS and LHCb. Further information: https://lhc-deutschland.de/

Belle II Germany

The ErUM-FSP Belle II is an association of all German institutes participating in the international particle physics experiment Belle II in Japan, where they are using precision measurements to research new insights into the elementary building blocks of nature. Further info: https://www.belle2.de/

Belle II gets a new heart: The new pixel detector PXD2 has arrived in Japan

18.03.2023

A powerful successor for the innermost detector

At the moment, the SuperKEKB accelerator in Japan is at a standstill. One of the main reasons for this is the planned installation of the new two-layer Belle II Pixel Vertex Detector (PXD2). The greatly improved small detector, which is responsible for measuring the shortest-lived particle decays in the Belle II detector, is scheduled to replace the current PXD1. This is necessary in view of future data taking periods with higher luminosity and the associated larger hit density on the sensors located only a few millimeters from the beam axis to avoid performance degradation for physics analyses.

Intensive preparation for the exchange

The PXD2, like its predecessor, was mostly built at the German institutes of the collaboration. The DEPFET active pixel sensors itself and the modules were developed and manufactured exclusively at the MPG HLL. After many months of intensive preparation at the various German institutes, the time had finally come: the two half-shells of the new PXD2 could be sent on the long journey to Japan. The small sensitive detector consists of ultra-thin and therefore fragile silicon sensors, which have to be protected against shocks in the best possible way. The transport of this unique and irreplaceable instrument was therefore a very special challenge.

The PXD2 was allowed to travel to Japan as a special passenger

In order not to let it out of sight for a moment, a separate seat was reserved for the detector on the aircraft. Bypassing the queues of waiting passengers, the special passenger was then let onto the aircraft first and stowed safely in his seat. To the great relief of all involved, an initial visual inspection of the two half-shells after arrival at the KEK showed no evidence of transport damage.

An important step towards new physics results

In the next few weeks, the detector will be mounted on the beam pipe, which is also new and manufactured at the KEK, and connected to the readout electronics to also verify full electrical functionality. In winter 2023-2024, the SuperKEKB should finally be put back into operation and we expect new exciting results.

The German working groups in the Belle II experiment are supported with funding from the following institutions and programs:

  • Alexander von Humboldt Foundation
  • Bundesministerium für Bildung und Forschung (BMBF)
  • Deutsche Forschungsgemeinschaft (DFG), insbesondere im Rahmen der Exzellenzstrategie des Bundes und der Länder:
    • „ORIGINS“: EXC-2094 – 390783311
    • “Quantum Universe”: EXC-2121 – 390833306
  • European Research Council
  • European Union’s Horizon 2020 – grant agreement No 822070
  • Helmholtz-Gemeinschaft
  • Max-Planck-Gesellschaft

Allen Caldwell is new executive director at the Max Planck Semiconductor Laboratory

17.01.2023

Physicist Allen Caldwell is the new Managing Director at the Max Planck Society's Semiconductor Laboratory (HLL), effective immediately. In this role, he works closely with Jelena Ninkovic, who is the head of the HLL and responsible for operation of the lab. Allen Caldwell succeeds Siegfried Bethke, now director emeritus, who headed the HLL from 2013 until the end of 2022.

The HLL emerged from a collaboration between the Max Planck Institutes for Physics (MPP) and for Extraterrestrial Physics with the goal of producing highly specific sensors for experiments in astrophysics and particle physics. Since 2013, the HLL has been a central facility of the Max Planck Society; administration remains with the MPP.

MPP Director Allen Caldwell took up his new post on January 1, 2023. He sees his primary task as aligning the HLL strategically and in terms of personnel to meet future demands of ambitious research projects. An important role will be played by partnership with the Munich Quantum Valley, a research alliance for the development and establishment of competitive quantum computers in Bavaria.

Relocation to Garching to begin in 2023

The relocation to the Garching Research Center, planned for the end of 2023, will entail further management tasks. High-quality and sensitive equipment is located at the HLL and its transport and commissioning will require a considerable amount of time.

The new location opens a new chapter for the HLL, as Allen Caldwell explains: "The new building has significantly more laboratory space than the current location and the technical plants meet the latest standards, allowing us to expand into completely new areas for research into innovative technologies based on different materials." In addition to developing sensors for ongoing and future projects, the HLL will perform research in sensor technologies for future fields of application independently of projects.

Highly specific sensors for physics experiments

The HLL develops and manufactures one-of-a-kind silicon modules that are used in sensors of physics experiments - for example, in the Belle II experiment in Japan, where unique technology developed by the HLL allowed for the deployment of an extremely thin pixel detector. This is being used to research the antimatter puzzle of the universe. In a current project, the HLL is building modules to detect sterile neutrinos in the KATRIN experiment at the Karlsruhe Institute of Technology.

"The HLL has a fantastic record of developing sensors for groundbreaking research projects," says Allen Caldwell. "This achievement is the result of outstanding efforts by the staff. I look forward to helping the HLL continue this successful journey and to working with Jelena Ninkovic, with whom I have collaborated closely with in the past, as well as to a strong partnership with the central administration of the MPG."

First prototypes of DMC 65 Integrated cuircit (IC) operational

29.11.2022

The EDET-DH80K camera system is a Direct Hit Electron Detector to be operated in the focal plane of a TEM. It is a one Megapixel camera system consisting of four independent quadrant modules with 256k pixels each, designed to operate at a framerate of 80k frames per second. Framerates even higher than that are possible by using advanced windowing techniques. The final system is capable of recording image bursts of 50 full frame images with the specified time resolution of 12.8 microseconds, with burst repetition rate of 100 Hz.

The system’s detector matrix is based on the combined DEPFET detector/amplifier cell. In addition to the unprecedented operation speed, the system features high radiation hardness, nonlinear amplification applying in-pixel signal compression and thinned detector substrate for optimum PSF. For maximum integration density inside the TEM column, the complete front end electronics is integrated together with the detector matrix on an All-Silicon Module (ASM).

A vital component of this system is the DMC 65 IC. Being a part of the front end electronics package, this device, a combined sequencer / data buffer IC is used as fast digital data handler IC for the modules and enables the system to operate with the specified time resolution. It consists of an integrated sequencer providing the control signals for the detector matrix, interface circuitry to the DCD digitizer chip used to acquire and digitize the analog data from the DEPFET matrix, and FIFO circuitry for capturing and buffering the DCD output data, which is then transferred to the periphery using the serial high-speed AURORA protocol. Each DCD is paired with one DCD chip, so the fully populated module will be furnished with 8 DCD/DMC 65 couples.

First light for EDET prototypes at TEM

First results of novel electron detectors for TEM imaging

11/26/2020

EDET DH80K is a novel focal plane instrument for transmission electron microscopy, which is done by the HLL in collaboration with the Max-Planck-Institute for structure and dynamics of matter in Hamburg. It is used for direct electron imaging in the focal plane of transmission electron microscope. Key features of this system are the fast imaging rate of 80 kHz, i.e. 13 µs per frame, for a 1024 x 1024 pixel sensor with 60 x 60 µm2 pixels, allowing for large-area imaging with a time resolution unprecedented at a TEM system. In addition, the system adopts innovative technologies like SOI based detector material and thinning to improve spatial resolution or nonlinear pixel characteristics to boost the systems dynamic range.

Now, a small-area prototype sensor for this system could be successfully integrated into and operated within the TEM environment. The sensor prototype had 64 x 128 pixels and a substrate thickness of 30 µm only. The interplay of sensor system and electron radiation could be demonstrated and investigated for the first time, and measurements of the dynamic range properties and imaging performance were conducted. This successful campaign is an important milestone on the way towards operation of the large area devices and a big achievement in challenging project.

BELLE II DELIVERS FIRST RESULTS

In search of the Z’ boson

04/07/2020

The Belle II experiment started almost exactly a year ago. The renowned journal Physical Review Letters is now publishing the first results of the detector. The work deals with a new particle in connection with dark matter, which, according to current knowledge, makes up about 25 percent of the universe.

The Belle II experiment has been taking data for physical measurements for about a year. Both the SuperKEKB electron-positron accelerator and the Belle II detector had been refurbished over several years in order to achieve a 40 times higher data rate.

Scientists at twelve institutes in Germany are significantly involved in the construction and operation of the detector, the development of evaluation algorithms and the analysis of the data. The Max Planck Society's semiconductor laboratory made a key contribution to the new development of the highly sensitive innermost detector, the pixel vertex detector.

With Belle II, scientists are looking for traces of new physics that can be used, for example, to explain the unequal occurrence of matter and antimatter or the mysterious dark matter. One of the previously undiscovered particles that the Belle II detector is looking for is the Z'-boson - a variant of the already detected Z-boson. The latter acts as an exchange particle for the weak interaction.

As far as we know, about 25 percent of the universe is made up of dark matter, whereas visible matter makes up just under 5 percent of the energy budget. Both forms of matter attract each other via gravity. Dark matter forms a kind of template for the distribution of visible matter, which is shown, for example, in the arrangement of galaxies in the universe.

Link between dark and normal matter

The Z'-boson could play an interesting role in the interaction of dark and normal, visible matter, i.e. it could be a kind of mediator between the two forms of matter. The Z 'can - at least theoretically - result from the collision of electrons (matter) and positrons (antimatter) in the SuperKEKB and then disintegrate into invisible dark matter particles.

Thus, the Z'-boson can help to understand the behavior of dark matter - and not only that: the discovery of the Z 'could also explain other observations that are not in line with the standard model, the fundamental theory of particle physics .

Important indication: detection of muon pairs

But how can the Z'-boson be found in the Belle II detector? Not directly, that's for sure. Theoretical models and simulation calculations predict that the Z 'could reveal itself through interactions with muons, heavier relatives of the electrons: If, after the electron / positron collisions, scientists have an unusually high number of muon pairs with opposite charges as well as unexpected ones Discovering deviations in energy and momentum conservation would be an important indicator for the Z '.

However, the new Belle II data did not yet show any signs of the Z'-boson. However, with the new data, the scientists can limit the mass and coupling strengths of the Z'-boson with an unprecedented level of accuracy.

More data, more precise analyzes

"Despite the still small amount of data, we can now take measurements that have never existed before," said the spokesman for the German groups, Prof. Thomas Kuhr from LMU Munich. "This underlines the important role of the Belle II experiment in the research of elementary particles."

These first results come from analyzing a small amount of data that SuperKEKB started up in 2018. Belle II started full operation on March 25, 2019. Since then, the experiment has been collecting data, while the collision rate of electrons and positrons has been continuously improved.

If the experiment is set up perfectly, it will provide a multiple of the data that has gone into the currently published analyzes. The physicists hope to gain new insights into the nature of dark matter and other unanswered questions.

 

The German working groups in the Belle II experiment are funded by the following institutions and programs:

Federal Ministry of Education and Research: Framework Program for Research on Universe and Matter (ErUM)
German Research Foundation (DFG) as part of the excellence strategy of the federal and state governments:
"ORIGINS": EXC-2094 - 390783311
"Quantum Universe": EXC-2121 - 390833306
European Research Council
European Union’s Horizon 2020 - grant agreement No 822070
Helmholtz Association
Max Planck Society

 

Publication:

Search for an invisibly decaying Z 'boson at Belle II in e + e– ® m + m– (e + - m– +) + missing energy final states

The Belle II Collaboration

Physical review letters; Volume 124, 14; April 10, 2020

URL: https://link.aps.org/doi/10.1103/PhysRevLett.124.141801
DOI: 10.1103 / PhysRevLett.124.141801

Go to Editor View