05|13 Newsletter of the Research Centre DESY Messengers from the high-energy universe First CTA prototype starts tests in Berlin In 2018, the CTA will be more sensitive than the existing gamma observatories. Illustration: DESY/Milde Science Comm./Exozet Star explosions, black holes, giant Telescope Array will observe thousands maelstroms – the Cherenkov Telescope of these accelerators with unprecedented An eye on the pulse 3 Array CTA will open a new window to a sensitivity. It will be the gamma astronomy New concept saves power at detectors violent cosmos. On 22 May, at the Berlin observatory of the future.” Science Park Adlershof, the first medi- Honorary member 7 um-sized prototype of the planned three The CTA, developed in an international DPG distinguishes Herwig Schopper CTA telescope types enters the testing cooperation, will observe cosmic high- phase. It was designed and built by the energy gamma rays and will consist of Helpers want 8 DESY institute in Zeuthen. three different-sized telescope types Open day in Hamburg with sensitivity for different energy ranges. “The universe is full of natural particle DESY is the largest group within the inter- accelerators, for example in supernova national project and is responsible for At the prototype in Berlin Adlershof, the explosions, binary star systems or active design and construction of the medium- mirror suspensions, the drive and safety galactic nuclei,” said Christian Stegmann, sized telescopes with a mirror diameter system and the rest of the mechanical head of the DESY institute in Zeuthen of about 12 metres. “These will be the system will be tested in the coming near Berlin. “So far, we know only about ‘working horses’ of CTA covering the core months. In the coming year, an alternative 150 of these objects and we begin to area of gamma ray energy of 100 to mirror carrier will be mounted and tried understand the physics of these 1000 Giga electronvolts,” said Stegmann. fascinating systems. The Cherenkov CONTINUED ON PAGE 2 DireCtor’sDIRECTOR’S CornerCORNER Dear colleagues, necessary to interrupt FLASH operation. In parallel construction has started for the new FLASH II experimental hall. From the beginning of those who access the campus from the side entrance at Luruper 2014, the first of five beamlines will generate light for first experiments. Chaussee and proceed in direction of the FLASH II construction site may have noticed the open areas which emerge at DESY. Guest houses have Not quite as visible as all the building work is the successful setup of been torn down, roads have been relocated and trees have been logged the expertise in the field of laser research and development in the past to make room for future photon science projects. Two new experimental years, which is extremely important for the further development of halls of the PETRA extension, hall east neighbouring the physics FLASH and the European XFEL. Ingmar Hartl came on board at the institutes of the university of Hamburg and hall north adjacent to the beginning of 2013 as head of the new group for laser development and FLASH experimental hall, will be coordinated and erected at the same operation, which will develop and operate novel lasers for accelerators time as the construction of the new building for the Centre for Structural and experiments. Systems Biology (CSSB). Construction is supposed to start in July; if everything goes according to plan, the first ten new PETRA III beam- All these developments would be unthinkable without the successful lines in both halls could already be available to scientists at the research done at DORIS for more than 30 years, laying the cornerstone beginning of 2015. not only for future research with synchrotron radiation. We will look back on the pioneering experiments which paved the way for ground- The construction work for FLASH II, which has been delayed a bit breaking research worldwide during the DORIS DAYS on 14 and 15 May. because of the long winter period, is now making good progress. Construction of the tunnel carcass and the entrance building will be Yours, completed within the coming weeks; the technical infrastructure is now Edgar Weckert being installed on site. Connecting the two FLASH tunnels makes it out. When, in 2015, construction starts Not only CTA promises new insights Already now, scientists are thinking for the real observatory, the prototype into cosmic particle accelerators. The about the extension of the giant detector will also move to this site. However, a neutrino telescope IceCube at the South which currently has more than 5000 photo­ decision has not yet been made upon Pole, with DESY as the second largest multipiers within one cubic kilometre of the location. There are plans for one in group after the University of Wisconsin­ eternal ice, scouting for the rare collisions the southern and one in the northern Madison, delivered first hints of high- of cosmic neutrinos. A proposal named hemisphere. energy cosmic neutrinos. “An exciting PINGU plans to deploy extra photo­ time is beginning at IceCube: after the multipliers into the ice in the inner zone In its commitment for CTA, DESY benefits construction phase of many years, we of IceCube. As an alternative – or in to a great extent from the experience will now bring in the scientific harvest,” addition – the detector could be extended gained at other gamma observatories. said Stegmann. with another 80 strings of photomulitpliers With groups at VERITAS and MAGIC on in the outer zone; the proposal has the the northern hemisphere and H.E.S.S. working title IceCube++. Zeuthen scien­ Bessel laureate in Zeuthen on the southern hemisphere, DESY The Spanish astroparticle physicist Diego tists are participating in the assessment participates in all large gamma obser­ F. Torres from the University of Barcelona of both options. vatories on earth, and also in the gamma received a Friedrich Wilhelm Bessel space telescope “Fermi” − in connection Research Award granted by the Alexander IceCube and CTA complement each von Humboldt Foundation and will come with Markus Ackermann and Rolf Bühler, other on the way to a common important to Zeuthen for a research stay. In the group who recently was awarded the Shakti­ of Elisa Bernardini, Torres will work among goal, as Stegmann emphasises: “We P­Duggal Award for astroparticle physics. others on time­dependent phenomena investigate two cosmic messenger “This is a great advantage, because we in the high­energy cosmos. The Friedrich particles, neutrinos and photons. This are perfectly linked up and can build on Wilhelm Bessel Award includes a prize will help us to understand how the high­ a broad range of experiences and are money of 45 000 euros and is presented energy universe works.” (tim) to renowned scientists from abroad to familiar with different cultures. With this, facilitate joint research projects with we are perfectly prepared for CTA,” colleagues in Germany. Stegmann emphasises. An eye on the pulse New powering scheme tested at DESY saves space and money The complete detector setup of the prototype in the test beam. The small silver box (lower right) provides the innovative power supply Sometimes scientists tackle problems from unexpected angles. Future particle The linear collider’s pulsed beam cycle detectors like the ones for the Inter- would easily allow for running the to be no extra signal from the power national Linear Collider ILC or the detectors in power-pulsing mode, so supply, which means that the signal is Compact Linear Collider CLIC will face detector developers have started just as clean as in continuous mode,” many challenges, some of which are building prototypes to test whether their explains engineer Remi Cornat from the similar to those of the running detectors idea would work in real life. One such French lab Leprince-Ringuet (LLR). at the Large Hadron Collider LHC, and prototype delivered proof of power- some are very different. One such pulsing principle earlier this year in a Detectors are supposed to see a clear challenge is space: there is notoriously test beam at DESY: a Franco-Japanese signal of the processes relevant to the little of it, because the sophisticated collaboration working on a calorimeter physics phenomena that are being particle tracking and identification for the ILD detector at the ILC tested studied, but because of electronics, methods leave no room for ‘dead space’ their technological prototype in pulsed currents and various materials there is and it all needs to fit into the confines of mode both with beam and in a magnet. no such thing as 100% signal – there is the detector’s powerful magnet. Results were promising: “There seems always a little background noise. Keeping the noise down is crucial for good So scientists working on detector proto- results. Scientists were worried that the types for the ILC came up with the idea new powering scheme might have a to save space by reducing the space- negative influence on the ratio of signal eating cooling mechanism for the to noise, but there seems to be no electronics and sensitive materials. In effect. The next step is a refined version order to make sure that the components of the detector, with more channels, don’t overheat without cooling, they had more chips, more front-end boards that another invention: a new powering will grow to more than three times as scheme called power pulsing. In power- many layers as it is now and a total pulsed mode the detector electronics length of two metres. Then there’s more are only powered up when collisions are testing to check the reliability and about to happen; inbetween cycles they predictability of the new system. (baw) go in a sort of stand-by mode.