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ETH Zürich - D-PHYS - Solid State Physics - Microstructure Research - Collaborations - APE-ELETTRA


Selected Article

Nat. Comm 7, 13611 (2016)
Critical exponents and scaling invariance in the absence of a critical point

Proc. R. Soc. A 472, 2195 (2016)
Thirty per cent contrast in secondary-electron imaging by scanning field-emission microscopy
Phys. Rev. B 89, 014429 (2014)
Domain-wall free energy in Heisenberg ferromagnets

Phys. Rev. B 87, 115436 (2013)
Scale invariance of a diodelike tunnel junction

APE Beamline Report to the Commissione Luce di Sincrotrone:
Progress Report of the year 1999

15 March 2000, Giorgio Rossi
The scientific case for the APE project has not been weakened by discoveries or events in the last year.
The activity of all the groups involved in APE has continued with their pre-existing means in the fields of Fermi surface measurements, (University of .Zuerich), time resolved magnetometry on ps time scale (ETHZ), time resolved surface magnetometry at ns time scale (Modena-APE-LURE), core level dichroism (APE-LURE-ALOISA). A main technical development plan for time resolved measurements with 10 ps scale resolution, low gitter and large data rate handling, has been discussed and planned with a joint effort of the Detectors Group of ST and the Service Electronique of LURE. We are seeking specific financing of this part of the project which has developed beyond the original APE budget plans. Scientific proposals for the use of the existing beam-lines at ELETTRA by APE scientists have been deposited in order to develop the research programs that await the commissioning of APE for a full development, as well as to test some of the APE instrumentation.

1) Situation:

The APE project is in the construction phase. In the forthcoming weeks all of the main components of the beamline should be delivered. A complete picture of the status of the APE project as of 15 march 2000 is as follows:

a. The insertion devices are installed, including the kicking magnet to complete the zig-zag trajectory of the e-beam of ELETTRA. The tests of the insertion devices should be in progress by ST, but there appear to be delays in the software control of the undulators. This point will be clarified next week.

b. In December 1999 the whole APE area has been cleared from ST installations.

c. The front end and first security hutch (built by ST) are ready and tested, including the door interlocks and related protocols.

d. The secondary hutch (built by APE) is in place and is completed with door interlocks and related security gears. The lead wall has been delivered. It will be installed after the mirror chamber installation to fit the lead bricks to the tubes. The commissioning of the secondary hutch will require a day during the next shut-down of ELETTRA.

e. The workstation HP for the BCS (beamline control system) has been acquired by APE (from CICAIA-Modena) and will be installed by ST.

f. The power and fluids distribution system is being built at this time. (ST)

g. The APE-LE spectrometer (SCIENTA) is operational with a He-lamp. The RIAL manipulator and University of Zurich cryostat work correctly now. Sample temperatures <10K and energy resolution of <8meV have been measured. UHV conditions P<5E-11mbar are routinely reached after 3 days bakeout. The limiting factor of the energy resolution appears to be the broadening of the emission from the resonant He-lamp. A more serious problem concerns the lack of intensity from secondaries. The transmission of the SCIENTA is severely reduced for electrons between 0 and 5 eV of kinetic energy. This symptom is common to other analyzers of the same kind (LOTUS-Modena, LURE...). We have measured a large magnetic field leaking along the mu-metal "nose" of the analyzer. We have compensated the field by applying an external opposite field with a coil around the analyzer lens. We have carefully mapped the magnetic field inside the chamber. We will measure the results of this after the current bake-out. If problems in the low energy part of the spectrum and/or in the angular distribution of intensities will persist further actions to be taken will be: 1) a thicker and better connected mu-metal shield, a demagnetization of the SCIENTA analyzer lens. This last procedure is somewhat delicate, but was prooved to be effective to solve the problem in Baer's laboratory at the Universite de Neuchatel. The low kinetic energy problem does not hinder the possibility of experiments with the He-lamp, but must be solved in view of the low photon energies to be used on APE-LE. The LEED has been mounted and will be tested. Currently a scientific experiment on the Fermi level emission from a monolayer of C60 onto Ag(110) is starting (APE + TASC). One student from Modena (Gianluca Selvaggi) supported by the INFM-LdS bourses bando 234, is working on this project.

h. The APE sample preparation and characterization chamber is operational with Co, Fe sources, Kerr effect, magnetization coils, LEED-Auger, STM. The UHV conditions are 2E-11 mbar after two days bake-out. Currently a test experiment on Co(1010) is being carried out. An experimental program on Pt-Co surface two-dimensional alloys is planned for the next weeks (APE+Maurizio DeSantis-Grenoble). One student from Modena (Fulvio Codegnani) supported by the INFM-LdS bourses bando 234, is working on this project.

i. A UHV chamber has been assembled for testing the Mott detectors with an e-gun. The electrostatic lens of the Mott detector has been assembled and wired. The HV power supplies have been recently delivered and tests are planned in the forthcoming weeks. (APE + Miriam Padovani-Brescia). The electronics for counting has been built by the Detectors Group of ST and will be tested as soon as the whole assembly will be ready.

In 1999 the APE team (Giancarlo Panaccione and Giorgio Rossi, later also Ivana Vobornik and Jorg Kroeger) has undertaken the following actions:
1. Completion of main purchasing/tender processes: All main contracts have been signed in 1999. ISA Italia signed on May 10th for the monochromators, Beamline Technology Co. signed on 20/09/1999 and Ibsen finally signed on 25/10/1999. Those facts do have an impact on the schedule since, formally, the delivery terms are calculated from the signature. The contractors are quickly reaching the delivery time limits and APE will make a point within next April on the situation.

2. The construction of the first switching mirror chamber has been attributed to RMP.

3. Mr. DeLuisa, Mr. Maier (ETH), Dr. Panaccione and Dr. Back have developed the sample transfer system in collaboration. The construction has been attributed to the PINK Company (Germany). The system is scheduled for delivery in April 2000.

4. The cryo-cooling of the APE switching mirrors has been designed with P. Gifford of CRYOMECH and purchased. Delivery is expected in April-May 2000.

5. Mr. Joerg Kroeger has joined the APE group in August 1999. He is a 3rd year Ph.D. student at the University of Zuerich at Irchel. Dr. Ivana Vobornik has obtained an INFM post-doctoral position after a competition for a 2+2 years contract. She started November 1st and took the lead of the commissioning of the APE-LE spectrometer.
a. ISA-Italia, monochromators: on 27 October the following items were finally approved: exit slits, APE-HE monochromator. The APE-LE monochromator were approved in Nov. 1999.

b. RMP switching mirror chamber: The contract has been signed on 19/07/99. Final drawings were approved in Nov. 1999.

c. BTC mirrors: The contract has been signed on 20/09/99. The mirrors have been produced and tested at Advanced Photon Source (Argonne). APE has not yet received reports on quality tests.

d. Ibsen gratings: The contract was signed on 25/10/99. The gratings for APE-HE are built on blanks from BTC. These blanks have been produced and tested at APS (Argonne) the slope error is 0.8micro-rad instead of 0.5micro-rad specified. The excess slope error is attributed to gravitational sag due to the relatively thin blanks. We decided to accept those blanks and to authorize Ibsen to proceed with the gratings. The gratings for APE-LE will be built on blanks from SESO.

e. RIAL: The UHV translator/manipulator has finally been modified and now it works.

f. Varian: All pumps were delivered and stored at ELETTRA.

g. SAES-GETTERS: All pumps were delivered and are stored at ELETTRA.

h. Varian valves: All valves have been delivered.

i. Caburn valves: Most valves have been ordered and have been delivered and stored at ELETTRA.

j. PINK: Transfer chambers and systems have been designed and purchased. Delivery is expected in April 2000.

2) UPDATE OF PROJECT (Modifications done in 1999 to the original project)

a) Design and tender for Entrance Switching Mirrors:

The gas He refrigerator system has been chosen for maintaining the entrance mirrors at T<125K. Mr. P. Gifford, president of CRYOMECH, was at ELETTRA for a work session with the APE group and with the engineers of RMP. The system has been approved and purchased.

b) An order for extra blanks (polished flat to 0.5microrad max. slope error) was made to Ibsen. These extra blanks are needed as replacement mirrors for the gratings.

d) The general layout of the beamlines has been refined. The layout of electricity, gas, water services has been designed and approved by ST. We have asked for a special ground track made by a 4mm thick copper plate 30cm wide, running all along the beam lines. The beam line itself will be electrically isolated from ELETTRA by a ceramic break between the switching mirror chamber and the front end. All the ground connections will go to the copper strip, which will be connected to only one ground point of the building.

These installations are in progress now (march 2000, with a 5 months delay).
g. On October 25th APE-LE moved to the final place. In December 1999 the whole APE area has been cleared from ST installations.

h. The analyser for the Spin Resolved Fermi Surface Mapping and two Mott detectors were delivered and tested at University of Zuerich. The tests went well. The electron switch for this system is under construction at Irchel.

i. The 6-axis manipulator built at Irchel is delayed since it did not reach the specifications of low temperature yet. T<30K is expected.

j. The computer code for running the angular scans and the SCIENTA analyser has been completed by Joerg Kroeger and successfully tested.

Manpower for APE-LE spectrometer: Joerg Kroeger (Uni. Zuerich) has started in August 1999. Dr. Maurizio DeSantis of CNRS-Grenoble has joined the APE-LE group for 4 weeks in June-July 1999. Gianluca Selvaggi, a laureando from Dip. dell’Universita' di Modena e Reggio Emilia, has joined the APE-LE group in January 2000 for his thesis group.
l) The APE-HE design of refocusing and spectrometer has been completed. An aspherical mirror has been designed and calculated by F. Polack for a spot of about 3 micrometer times 10 micrometers full width at half maximum on the sample. This includes the slope errors that for an ellipsoid are of the order of 5 microrad or more. A rough offer for such mirror has been made by SESO for 400-450 KFRF. The decision is pending upon the results of BTC mirrors.

Offers for the construction of 5mm-thick UHV chamber for APE-HE have been received (40MLit +taxes). Decision is pending upon definition of final mechanical details.

A second plane mirror will be inserted in the beamline, just in front of the focussing mirror when the alternative Fresnel zone-plate scheme of focusing will be operated. In this case we will reach typical features of lateral resolution <100 nm with >20% efficiency, or better lateral resolutions with reduced, but still large (>5%) efficiency. A very useful discussion on the zone-plates has started with Drs. DiFabrizio and Romanato of the LILIT project.
o) The ETH system was imported and delivered at ELETTRA in December 1999. A post doctoral fellow, Dr. Stefan Egger, has joined the APE group in February 2000. Fulvio Codegnani, from Modena has started in January 2000 his laurea thesis work on this system (Kerr effect of Co/Pt system).

4) Logistic and technical support

4a) We have used the technical support of Aleksander Deluisa for chambers, transfer system, general layout, development of new mechanical systems.

We have used the tecnical support of Ales Gruben for construction of mechanical and UHV parts, chamber supports, sample holders

We have used the support of Fabio Suran and Andrea Martin for computer support, construction of electronic and electrical parts, netwoek connections.

We have used services from ST : electronics (Menk group), vacuum (Mazzolini), mechanics.

We expect to maintain a strong pressure on the tecnical and logistic services, which need to be strenghtened in view of the upcoming of all the beamlines. In particular the electronic support should be increased on the low level part (wiring, cabling, simple time consuming tasks) to free resourses for higher level jobs.
© 2018 ETH Zürich | Impressum | 2004-08-09 14:10:44