PERFECT CRYSTAL NEUTRON OPTICS

ERB-FRMX-CT96-0057

MID-TERM REVIEW REPORT

The Participants:

A.1 Scientific Highlights

The general advent of quantum optics also stimulated quantum optics with matter waves. Neutrons are a proper tool as they experience nuclear, electromagnetic and gravitational interaction and their decay is governed by the weak interaction. Inside a magnetic field they exhibit properties of a variable two-level system which can be manipulated by coupling to a resonance electromagnetic field. Newly developed methods based on neutron quantum optical principles can be used for measurements of fundamental laws of quantum mechanics and can be used for various high sensitivity measurements in condensed matter research, for a quantum based beam tailoring and for investigation of interpretational questions as well.

In the first two years of the network strong efforts have been made to

• Upgrade the neutron interferometer set-up at the high flux reactor of the ILL in Grenoble
• develop a multi-pulse neutron storage system at the pulsed neutron spallation source ISIS at the Rutherford Lab., U.K.
• develop a high precision method for accurate scattering length measurements
• formulate neutron experiments in terms of quantum optics

Fig.1: View of the new interferometer set-up at the ILL in Grenoble

A third axis has been added to permit various postselection experiments providing a better insight into the structure of a quantum state especially to the transformation of a quantum state into a mixed state due to dephasing and, decoherence effects. In this respect novel experiments are in progress to verify various theoretical predictions concerning undecided problems closely related to the general quantum measurement problem (Rauch et al. 1999).

The same optical bench is used for an improved perfect crystal ultra small angle scattering camera using channel-cut crystals (Bonse a. Hart 1965) and the new "Agamalian chop" (Agamalian et al. 1997) to reduce the tails of the multiple reflection rocking curves. Fig. 2 shows a typical measurement with a structured silicon plate having regular holes with a depth of 90 µm at a distance of 2.1 µm. Peak intensities up to 8000 n cm^-2 s^-1 have been achieved.
 
 

Fig. 2: Ultra small angle scattering pattern from a structured Si-plate
 

A very tricky method has been developed for very precise scattering length measurements which uses the non-dispersive sample position methods as tested previously (Rauch et al. 1987). The new method permits a very accurate adjustment of the sample to the reflecting planes of the perfect crystal interferometer by minimizing the overall phase shift (Ioffe et al. 1988; see Fig. 3).

Fig. 3: Scheme for an accurate sample orientation for very accurate scattering length measurements.

For a silicon sample an accuracy of 0.005 % has been achieved (b_c = 4.1507(2)). This also opens new possibilities for precise sample density and sample composition measurements and for the measurement of small phase shifts in general.

Very precise phase shift measurements have also be performed with a very-cold-neutron interferometer based on phase gratings where the gravitational phase shift has been measured with an accuracy of about 1 % and the non-dispersivity of the Aharonov-Bohm phase shift has been proven (Zouw et al. 1999).

The understanding of classical (coherent) and non-classical neutron quantum states has increased considerably since the Wigner- and Weyl-formalism has been introduced to neutron quantum optics, especially for the description of neutron interference and neutron spin-echo experiments (Rauch a. Suda 1988). Dephasing and decoherencing effects have been included as well, which sheds a new light on the quantum measurement problem and the theoretical limits of interaction free measurements and Zeno-effect phenomena (Hradil et al. 1998).
 
 
 
 

The perfect crystal neutron storage (resonator) system VESTA at the ISIS spallation neutron source is shown schematically in Fig. 4. During the period of the
 
 

Fig. 4: View of the VESTA neutron storage apparatus

network various improvements have been made to increase the storage up to 3 seconds and to feed more than one neutron pulse from the source into the resonator system. The simultaneous storage of up to 6 neutron pulses has been achieved which leads to a new conceptual quality in neutron storage experiments (Jericha et al. 1999). Fig. 5 shows typical results.
 
 

Fig. 5: Verification of multi-pulse storage in the perfect crystal neutron cavity VESTA.

A new system is under development which avoids the rapidly switching magnets at the entrance and exit crystal plates and uses between the crystal plates a neutron magnetic energy transfer system based on a Rabi flipper system (Alefeld et al. 1981).

A schematic view of the new system is shown in Fig. 6. An increase of the performance parameters by a factor of more than 10 is anticipated.
 
 

Fig. 6: Sketch of the new perfect crystal neutron storage system based on active energy transfer to the neutrons by a pulsed magnetic resonance system.

References to non-network papers:

Agamalian M., Wignall D.G., Triolo R., J. Appl. Cryst. 30 (1997) 345

Alefeld B., Badurek G., Rauch H., Z. Physik B41 (1981) 231

Bonse U., Hart M., Appl. Phys. Lett. 7 (1965) 238

Rauch H., Seidl E., Tuppinger D., Petraschek D., Scherm R., Z. Physik B69 (1987) 313

Rauch H., Suda M., Physica B141-143 (1998) 157
 
 

A.2 Joint Publications

Book

"Neutron Interferometry", H. Rauch, S.A. Werner, Oxford Univ. Press (submitted)

This book collects nearly all experiments and theoretical approaches to this field and it provides an overview accessible also to newcomers.
 
 
 
 

Scientific Articles – TMR Network PECNO

• BADUREK G., RAUCH H., SUDA M., WEINFURTER H., "Identification of Schrödinger cat-like states in neutron spin-echo systems", Phys. Rev. Lett. (in print). - Partner: 1 and 8
• HRADIL Z., "Uncertainty of quantum state estimation", Proc. 5^th Int. Conf. Squeezed States and Uncertainty Relations, 27-31 May 1997, Balatonfüred, NASA/CP-1998-106855, p. 671, Gorddard Space Flight Center/Greenbelt. – Partner: 12 and 1
• HRADIL Z., MYSKA R., SUMMHAMMER J., RAUCH H., "Quantum tomography: Renormalization of incompatible observations", Proc. of QCM Conference, Evanston 1998 (in print). – Partner: 12 and 1
• HRADIL Z., NAKAZATO H., NAMIKI M., PASCAZIO S., RAUCH H., "Infinitely frequent meaurements and quantum Zeno-effect", Phys. Lett. A229 (1998) 333. – Partner: 1, 5 and 12
• HRADIL Z., SUMMHAMMER J., RAUCH H., "Quantum tomography as normalization of incompatible observations" submitted to Phys. Rev. A (1999). – Partner: 12 and 1
• IOFFE A., VRANA M., "A nouvelle neutron-interferometry method of high-accuracy determination of neutron scattering lengths", Phys. Lett. A231 (1997) 319. – Partner: 6 and 13
• IOFFE A., JACOBSON D., ARIF M., WERNER S., FISCHER P., GREENE G., MEZEI F., "A new interferometric method used to measure the scattering length of silicon", Physica B 241-243 (1998) 130-132. – Partner: 6 and 13
• IOFFE A., JACOBSON D., ARIF M., WERNER S., FISCHER P., GREENE G., MEZEI F.; "Precision neutron-interferometric measurement of the coherent neutron-scattering length in silicon, Phys. Rev. A58 (1998) 1475-1479. – Partner 6 and 13
• JERICHA E., SCHWAB D.E., CARLILE C.J., JÄKEL M.R., LOIDL R., RAUCH H., "Storage of multiple cold neutron pulses with perfect crystals", Nucl. Instr. Meth. A (in print). – Partner: 1, 4 and 10
• KROUPA G., BRUCKNER G., BOLIK O., ZAWISKY M., HAINBUCHNER M., BADUREK G., BUCHELT R.J., SCHRICKER A., RAUCH H., "Basic features of the upgraded S18 neutron interferometer set-up at ILL", Nucl. Instr. Meth. A (in print). – Partner 1 and 2
• MIKULA P., VRANA M., WAGNER V., "Bragg diffraction optics in neutron diffractometry", Material Structure 4 (1997a) 110. – Partner: 13 and 6
• MIKULA P., VRANA M., LUKAS P., SAROUN J., STRUNZ P., ULLRICH H.J., WAGNER V., "Neutron diffractometer exploiting Bragg diffraction optics: a high resolution strain scanner", Proc. ICRS-5, Linköping, 16-18 June 1997b (in press). – Partner: 13 and 6
• MYSKA R., HRADIL Z., PERINA J., ZAWISKY M., HASEGAWA Y., RAUCH H., "Phase estimation in weak fields", acta phys. slovaca 47 (1997) 323. – Partner 12 and 1
• RAUCH H., ZAWISKY M., STELLMACH Ch., GELTENBORT G., "Giant absorption cross section of ultracold neutrons in gadolinium", Phys. Rev. Lett. (in print). – Partner: 1 and 2
• RAUCH H., SUDA M., PASCAZIO S., "Decoherence, dephasing and depolarization", Physica B (in print). – Partner 1 and 5
• REHACEK J., HRADIL Z., ZAWISKY M., PASCAZIO S., RAUCH H., PERINA J., "Testing of quantum phase in matter wave optics", Phys. Rev. A (in print). – Partner: 12, 5 and 1
• VRANA M., MIKULA P., LUKAS P., WAGNER V., "Two-wavelength sandwich monochromator for material research experiments" Physica B241-243 (1998) 231. – Partner: 13 and 6
• VRANA M., MIKULA P., LUKAS P., DUBSKY J., WAGNER V., "New Developments in Instrumentation for Strain Scanning in NPI Rez, In Proc. of the 6^th European Powder Diffraction Conference EPDIC-6, Budapest, August 22-25, 1998, Hungary (in print). – Partner: 13 and 6
• ZOUW VAN DER G., WEBER M., FELBER J., GÄHLER R., GELTENBORT P., ZEILINGER A., "Aharonov-Bohm and gravity experiments with the very-cold-neutron interferometer", Nucl. Instr. Meth. A (in print). – Partner: 8 and 2

PART B - COMPARISON WITH THE PROJECT PROGRAMME

A major goal of the network is the development of neutron quantum optics and the use of quantum optical phenomena for new experiments in fundamental and applied research and for an advanced beam tailoring. The perfect crystal structure imposes distinct coherence features on the neutron beam which permits experiments with non-classical neutron states and extends the spectroscopic measuring techniques to extremely high sensitivities. Such developments are also relevant for the planning of the next generation of advanced neutron sources like the European Spallation Source ESS and the Central European Project AUSTRON.

Moreover, since the time when the network objectives were formulated, the progress in atom, molecular and cluster matter wave optics has become impressive and this has a feedback effect for the neutron case where matter wave optics with an elementary particle opens new horizons for basic research.

B.2 Methodological Approach and Work Plan

The methodological approach described in the application has been shown to provide a sound basis for the work within the network. Three main elements of cooperation were defined and initiated during the first period of the network.

• Cooperation between neutron providers and neutron users

 
ILL, ATI, ISIS, UNIDO, HMI, UNIINS, PSI, NPI, KFA
 
• Cooperation between experimental and theoretical groups

 
ATI, UNIBARI, UNIINS, RISSP, UNIOL
 
• Cooperation with Industry

KFA, ATI, WACKER, HMI, UNIDO

Fig.7: Joint publication within the first period of the network
 
 

The effectivness of these cooperations is also shown in Fig. 7. It can be expected that the effectivity of the network increases in the second period because a lot of upgrading work had to be done in the first period and several new instruments are now ready for scientific use (S 18, VESTA).
 
 

B.3 Schedule and Milestones

The present status of the network schedule and its milestones are shown in the following Tab. 1. A comparison with the table in the network contract shows that most the promises have been achieved. A fourth year will be necessary to use the newly developed methods and instruments for scientific work.
 
 

B.4 Research Effort of the Participants

All partners of the network contributed to the output of the network. In most cases additional financial sources were necessary to fulfil the requirements to install new instruments. Moreover, during the recent years there was a lack of young researchers, especially in the experimental field. To fulfil the schedule more work was performed by local staff and thesis students instead of post-docs. An overview is given in Table 2.
 
 

B.5 Cohesion with Less Favoured Regions and Scientists in Central and Eastern Europe

The node UNIBA (Universita di Bari) is located in a less favoured region of the European Community. There is a strong cooperation with the nodes ATI and UNIOL and several joint papers have been produced. Saverio Pascazio (Scientist in Charge) and one of his PhD-students (Paolo Facchi) spent several month in Vienna and Olomouc.

The cooperation with the three partners situated the in Czech Republic (NPI, UNIOL) and in Hungary (RISSP) developed very fruithfully as it is documented also by several joint publications (Fig. 6). Long stay visits in Vienna and Berlin strengthened the cooperation considerably. The 1998 Network Workshop was held at Rez near Prague and brought together all network partners resulting in the definition of several new network proposals.

B.6 Network Organization and Management

The administrative management is done at the Atominstitut der Österreichischen Universitäten in Wien. One problem of some significance arised with the Cost Statements 1997 where parts of expenditures were listed under "Scientific Experiment" and some partners deducted the whole "Overheads" at the beginning (see Releve de Compete 14. July 1998 – Ref. Doc. 9807 899/014). In a following letter dated Sept. 1, 1998 its has been shown that the positions under "Scientific Equipment" are according to EC-definition "Consumables" because they are supplementary parts to the neutron interferometer instruments S18. This view has been accepted by the Commission by letter from Sept. 10, 1998 (f. du Bois de Vroylande – SDME 3/oZ). Therefore the related amount has now been added to the Annual Cost Statement 1998 under "Adjustments to costs previously reported".

Most information exchange within the network was performed via the internet. A special web-page (http://www.ati.ac.at/~neutweb/pecno/pecno.html) serves for internal and external exchange of information.

Several posters of the network were also presented at the TMR Review Conference of the European Commission held in Graz 6.-9. May 1998.

Several changes have been effected within the structure of the network:

• Changes of the Scientist in Charge Partner 2 (ILL):

 

 

From C. Zeyen to J. Kulda

The task leader A. Magerl left ILL for the University Erlangen-Nürnberg

• Changes of Associated Partners

 

 

Partner 8 (UNIINS)

Due to the transfer of Prof. A. Zeilinger from University Innsbruck to the University Vienna its has been applied to change the Associated Partner 8 from

Institut für Experimentalphysik, University Innsbruck

to

Institut für Experimentalphysik, University Vienna




• The following external affiliated co-workers have been defined

P. Becker and V. Wagner (PTB Braunschweig) to HMI-Berlin

B.7 Connection to Industry

The close contact to the industrial partner (WACKER-SILTRONIC) was appreciated by many network partners and WACKER-SILTRONIC is the main supplier of perfect crystals needed for the work in the network. A working group "Crystals" was established which organized a topical Workshop in Burghausen (Germany) 11.-12. December 1997 where 11 scientists took part.

The cooperation with our industrial partner will be an essential part of the work in future as well.
 

PART C - TRAINING

As mentioned earlier during the recent years there was a noticeable lack of young researchers with sufficient experience in experimental physics. The situation is especially difficult with respect to recruitment of post docs because they have good chances in industry and in the public domain. Although the vacancies have been published in the magazines of various physical societies and the TMR and institute web-pages it was difficult to find qualified personnel. Most successful were personnel contacts during several topical conferences. Table 3 gives an overview about the employment situation (status 31.1.1999).

As a result of this situation the permission is requested to fill post-doc positions with advanced pre-docs. According to the different salaries the working period (man-month) for a pre-doc should be expanded by a factor of 1.5 compared to that of a post-doc.

C.2 Training programme

Mutual visits and the exchange of young researchers are the essential aspects of the cooperative work within the network. Visits between theoreticians and experimentalists, e.g.

and with the industrial partner

have taken place on a regular schedule

Another important training aspect are the workshops that have been organized

TMR-Kick-off-Workshop 11.-13. April 1997 held in Vienna

41 participants (26 external), two working groups have been introduced:
 
a) Crystals
b) Theory
• Crystal Working Group Meeting, 11.-12. December 1997 in Burghausen/DE, 11 participants

• TMR-Workshop 25.-28. June 1998 held in Rez near Prague

40 participants (34 external)

Several other meeting of subgroups have taken place in connection with International Conference, e.g. Int. Conf. Neutron Scattering, Toronto, 17.-21. August 1997, - AUSTRON Advisory Bord Meeting, 30 June and 1. July 1998 – Int. Workshop on Polarized Neutrons, Grenoble, 21.-23. September 1998.
 
 

C.3 Factual Information on the Young Researchers

Table 4 gives an overview about the Young Researchers financed by the network (status 31.1.1999).
 
 

PART D - SKETCHES OF THE YOUNG RESEARCHERS

Theodor BIERMANN (ATI)

At February 1998 I finished my PhD at the University of Dortmund in the special field of X-ray interferometry and I was occupied there for the following 6 months as postdoc. In the last years of my activities at the University of Dortmund I worked in the XTM group (X-Ray Tomography Microscopy).

We studied samples of industrial and medical areas with the absorption X-ray microtomography and the new method of X-ray-phase contrast tomograhpy pXTM. The measurements were practicized by using synchrotron radiation at the DESY at Hamburg, Germany, and at the ESRF at Grenoble, France.

By my employment as a TMR postdoc at the Atominstitut der Österreichischen Universitäten I got the chance to test the tomograhpy with (monochromatic) neutrons at S18, ILL at Grenoble, France. The studied sample was a ball bearing made of steel and plastic, which I could reconstruct and visualize in three dimensions.

While my period as TMR postdoc I felt the international exchange of know-how and experience as well as the friendly cooperation of all participants as very positive.

I hope, that these kind of projects will contribute to the fact, that people of different nationalities will learn to treat each other without prejudices in a sincere and understanding way.

Unfortunately the different national facts concerning social insurance, tax and so on cause unfavourable conditions.
 
 
 
 

Martin JÄKEL (ISIS)

While studying at the University of Linz, I started the work for my diploma theses at the Atominstitut Vienna (ATI) and gained my first experiences in neutron quantum optics, especially in storing cold neutrons by perfect single crystals, in the group of Prof. H. Rauch. After finishing my diploma theses in 1997, I kept working at the same project VESTA (the Viennese nEutron STorage Apparatus ) for my doctoral theses.

This TMR network gives us the opportunity to work at the VESTA beamline at the ISIS facility for more then a couple of weeks per year, giving us good knowledge about the limiting parameters of the current setup and will help us constructing an improved version of this neutron optical tool.

For me it is the first chance to work at one of the world's leading neutron sources. It also gives me the opportunity to meet interesting people at conferences and especially at the TMR workshops. Staying at ISIS is a good chance to extend my interests to the big field of neutron scattering, also a more precise definition of the training aspect of TMR would be appreciated.

All in all I do think that this TMR fellowship is an important step in my scientific career.

Erwin JERICHA (PSI)

Having obtained my PhD degree in 1997, after working in the field of neutron optics for several years under the supervision of Prof. H. Rauch (ATI Wien), I joined the Laboratory for Neutron Scattering at the PSI (Villigen, Switzerland) as a post-doc in the same year within the framework of the TMR network PECNO. This position allowed me to carry out my neutron optics' research in several areas. On one hand it allowed me to continue an existing collaboration with the ISIS Facility on perfect crystal neutron storage cavities (a direct continuation of my thesis work), on the other hand I was offered the possibility to condense my knowledge in the field of neutron optics into the design of a new instrumental set-up for related research at PSI. This project has been initiated as a collaboration with the ILL (Grenoble, France) and the Atominstitut Wien. In this respect, I was given the possibility to work at and in collaboration with the world's strongest stationary and pulsed neutron sources by the TMR network.

The new instrument (NOB) at the SINQ neutron source at PSI is designed to host a variety of different neutron optical set-ups with possible applications in a wide range of scientific research, which extends from fundamental nuclear physics and quantum mechanics to investigations of technological relevance like silicon wafers, micro-emulsions and magnetic materials. Following the integration of the NOB-concept into the SINQ instrument set and the technical implementation of the basic instrument components during my fellowship, the NOB instrument will commence test operation in March 1999.

Regarding the training aspect of TMR, I could significantly increase my knowledge in neutron instrumentation and the operation of neutron spallation sources as well as in the field of neutron scattering in general and in magnetic excitations of condensed matter in particular. I already could apply this knowledge with my contributions to the Project Study 1998 of the Austrian spallation source project AUSTRON.

In November 1998 I commenced working as an assistant professor at the experimental department of the Institute of Nuclear Physics at the Technical University of Vienna. The scientific activities during my work in the TMR network contributed significantly to the decision that I was chosen for that particular position. Scientific collaboration with several network partners is ensured for the foreseeable future, so that the course of my further academic career is strongly influenced by the experiences and contacts I have made since the start of the neutron optics TMR network.

Dagmar Elisabeth SCHWAB (HMI)

In order to finish my Diplom-studies in technical physics, I specialised myself in the field of neutron optics under supervision of Prof. Dr. Helmut Rauch and Dr. Colin Carlile.

For this reason I tuned up the Viennese Neutron Storage Apparatus at the pulsed Spallation source ISIS at RAL in England. It is a device for keeping cold neutrons inside a Perfect-Silicon-Crystal-Cavity. This advanced set-up and the new experiments drew us much more further in this technique of storing neutrons. TMR support contributed considerably to this project as well as to my stay in and to the travel to England.

Besides the great training effect in the field of silicon crystal neutron optics, I enjoyed the exchange of knowledge with foreign colleagues. And working at one of the largest neutron-sources of the world made my time at RAL even more exiting. The experience of performing experiments abroad did not only brighten my intellectual horizon, but also inspired me personally. Now, since January 1999, I hold a TMR-position at the Hahn-Meitner-Institute in Berlin. My interests are mainly concentrated on a double-crystal-diffractometer under supervision of Prof. Dr. Wolfgang Treimer and Prof. Dr. Helmut Rauch. I plan to construct a new version of a SANS-device. Therefore I have to prepare perfect Silicon-crystals at the Atominstitut in Vienna. TMR-network makes this collaboration possible. Building up a new device and performing new experiments with the expertise of the scientists there will very much extend my scientific experience. Discussions with the researchers at HMI makes the work extremely interesting for me!

I hope TMR-network will add one further year, so I will have the opportunity to realise and finish my plans.

Erik SJÖQVIST (ATI)

In 1955 I obtained my PhD in Qunatum Chemistry at Uppsala University. From March to June 1996 I worked as a postdoc in Prof. E. Squires group at University of Durham, England, before moving to Oxford University, England, for a two year postdoctoral stay working in the group around Dr. H.R. Brown. Both my PhD and previous postdoc work have been concentrated on fundamental problems of quantum theory. In January this year I started a TMR postdoc position within the "Perfect Crystal Neutron Optics" (PECNO) network, working ion Prof. Helmut Rauch´s group at the Atominstitut, Vienna.

My research as a TMR postdoc is focused on theory quantum phases in neutron interferometric and polarimetric experiments. In particular I am working on the evaluation of performed neutron interference experiments in terms of dynamical and geometric phases, as well as on the verification of the noncyclic geometric phase. I also work on aspects of the interaction between neutrons and electromagnetic fields, such as the topological Aharonov-Casher phase and related effects.

I have great expectations that my stay in Vienna as a TMR postdoc within the PECNO network will deepen and broaden my research on quantum phases, especially as I have the opportunity to interact directly with experimental expertise in this field.

Gerbrand VAN DER ZOUW (UNIVIE)

In 1997 I obtained my M.Sc. in neutron physics from the Technical University of Delft, the Netherlands. I then moved to Innsbruck, Austria to start work on the very cold neutron interferometer with Prof. Anton Zeilinger. Since January 1998 I am a young researchers within the PECNO network. This has given me the opportunity to interact with other people working on neutron interferometry through conferences and workshops. Because my experimental set-up is located at the Institute Laue-Langevin (ILL) in Grenoble, France, it is an advantage that the ILL is part of the network. Prof. Zeilinger´s group is a member of not only one, but three TMR European networks. For me this makes the work there especially worthwhile, because I can thus also participate in activities of the two other networks, giving me a truly interdisciplinary education.

PART E – NETWORK FINANCING

The following tables gives an overview of the payments and expenditures of the different partner institutions and in the last table an overview of the whole network. It is visible that relatively little expenditures happend mainly due to the problems in recruting post docs with proper experimental experience. Since the beginning of 1999 the situation has slightly improved but there are still vacancies to be filled.

Due to different exchange rates in different countries and at different times the accuracy of the numbers in the table is about ± 2% only. A more accurate bookkeeping can only be made at the TMR administration.