Technique for Parity Violation Investigations
Development of a Research Technique for Investigation of Fundamental Problems of Parity Violation and Time Reversal Invariance
Tech Area / Field
- INS-MEA/Measuring Instruments/Instrumentation
- INS-DET/Detection Devices/Instrumentation
3 Approved without Funding
Joint Institute of Nuclear Research, Russia, Moscow reg., Dubna
- ITEF (ITEP), Russia, Moscow\nNIIIT (Pulse Techniques), Russia, Moscow
- Forschungszentrum Jülich GmbH / Institute fuer Kernphysik, Germany, Jülich\nScience and Technology Facilities Council, UK, Didcot\nNorth Carolina State University, USA, NC, Raleigh\nInstitut Laue-Langevin, France, Grenoble
Project summaryThis proposal is the second part of the Project №608-97 ISTC: "Development of a Research Technique for Investigation of Fundamental Problems of Parity Violation and Time Reversal Invariance". The first part of this project was implemented within the framework of the Project №608-97. The full project with the same title was described in the Project Proposal and in Application I to the Project Agreement №608-97. The first part of the Project №608-97 ISTC was
Successfuly implemented.The results of the first part of the Project were highly appreciated by the foreign collaborators : professor J.B.Forsyth (RAL,England) and Dr. O.Zimmer (ILL, France). In the letter to M.Alan Gerard (Executive Director ISTC) professor J.B.Forsyth wrote: … I therefore strongly recommend that project participants receive the additional funding required to complete the three year project, in confident expectation that they will continue to perform to the same high standard and achieve all their objectives.
The project is dedicated to the development of an experimental technique for investigation of parity violation and time invariance violation with the use of polarized neutron beams and polarized nuclear targets. The development and construction of experimental setup for investigation of fundamental symmetries violation is a goal of this project.. Investigations in this domain is of basic impotance for understanding of a nature of fundamental interactions of elementary particles.
The construction of experimental installation of a such type is a very complex problem requiring a sequential solution of a series of intercommunicated methodical and engineering problems. The basic problems are following:
1) development of an optimum neutron beam polarizer and neutron beam analyzer which are based on the proton polarized targets - filters (PPF);
2) development of a polarized nuclear target (PNT) of large volume (> 100 см3), operating in the mode of "frozen polarization";
3) development of system for precise adjustment and control (SPAC) of the neutron beam polarization.
4) developmenta of method and equipment for a precision determination of a direction of polarization of neutrons.
The scientists from three institutes participate in Project :
1) Joint Institute of Nuclear Research (JINR, Dubna) - leading Institution;
2) State Science Centre, Institute for Theoretical and Experimental Physics (ITEP, Moscow) of Russian Atomic Energy Ministry;
3) Research Institute of Pulse Technique (RIRT) of Russian Atomic Energy Ministry. Since the Project №608-97 ISTC was funded by ISTC at 50 % level, it was pided into two parts.
Period of accomplishment of the first part of the Project: 01/12/97-31/05/99.
At the first stage, funded by ISTC with total amount 185 000 $, the main methodological and engineering problems necessary for successful realization of the project in whole were solved.
The following amount of works was carried out in the first part of the project:
· The block diagram of experimental installation was designed. The specifications for its basic components were developed. The algorithm of realization of measurings of physical effects and monitoring of possible false effects was designed.
· The test experimental setup including PPF-polarizer and PPF- analyzer was built at neutron beam N4 of pulsed reactor IBR-30 JINR. Now this setup is used for checking and improvement of engineering solutions of different parts of main setup.
· The spectrometer of polarized neutrons (including monocrystals Co-Fe as a polarizer and analyzer of neutron beam) was completed at the neutron channel №1 of the pulsed reactor IBR-2 JINR. This spectrometer provided possibility to test some parts of SPAC with use of time of flight method in several narrow energy ranges of neutrons.
· The test cryogenic setup was modernized in the cryomagnetic laboratory of Physical Institute RAS. This setup will be used for cryogenic and magnetic investigations of superconducting magnetic systems (SCMS), which must be developed during implementation of the project.
· The calculation, fabrication and test of a superconducting magnet for PNT was carried out. The the magnetic systems was developed in part for compensation of a PNT pseudomagnetic field and for fitting of magnetic field of polarized taergets and SPAC.
· The investigations of new substances as a target material for PPF were carried out. They are following: a copolymer of polyethylene – (propylene) and polysterol. Until recently they used as a target materials the substances which conserve their qualities only in the frozen state at temperature of fluid nitrogen. This makes difficult the storage and loading target material in PPF and essentially complicates a construction PPF wich must operate in the mode of frozen polarization. The new substances have large percent of hydrogen content and are rigid at room temperature. The method of fabrication of target material from this substances was developed. During the preliminary investigations of these target materials substances the proton polarization of 50 - 70 % was achieved. Using of a new target materials provide possibility to design PPF with loading of the target material and assembling of very low temperature part of PPF at room temperature. This is a great advantage which makes it possible to facilitate the PPF design and to reduce it price, besides it allows to unify desidns of PPF and PNT.
· The preliminary design of the superlow-temperature part of PNT operating in a mode of the frozen polarization was carried out. Provision was made in this design using of new substances target materials and new superconducting magnetic systems for PNT. It allows to unify practically all parts of PPF and PNT and safes time in the processes of development, fabrication and assembling of PPF and PNT.
· The specificstions on target material for the nuclear target were developed. The search for and synthesis of chemical lanthanum compounds having a cubic symmetry were carried out. The new method of dynamic alignment of the nuclei was proposed. An implementation of this method will open up new possibilities for investigation of time invariance and significantly increase the number of aligned nuclei accessible for experimenters in other fields of a nuclear physics.
· The calculations of a system for precise control of polarization of neutrons (SPCP) was carried out. The separate test units and devices of SPCP were fabricated and tested at the spectrometer of polarized neutrons (at IBR-2). The results of measurements and calculations coincided very closely..
· The development and fabrication of new microwave units and upgrading old one (necessary for a dynamic pumping of nuclear polarization) were carried out. A NMR-equipment for measuring of nuclear polarization in polarized targets was developed and fabricated.
· The systems for monitoring of the neutron beam intensity and for control of the parameters of the setup in scope envisaged by project schedule were developed and are applied in operation. These systems provides now reliable operation installation as a whole, and its separate parts used in the investigations.
Ultimate goal of the second part of the project is the assembly and adjustment of experimental installation for investigation of effects of violation of spatial parity and time invariance. Results of the second stage of the project will be :
1. The unified nuclear polarized targets working in a mode of frozen polarization.
2. A system for control of the neutron beam polarisation and for on-line measurement of polarization during experiment.
3. An apparatus for a precision measurement of rotation angle of the neutron beam polarisation plane.
4. System of a monitoring and of neutron flux
5. Computer system for the control of experimental setup.
The test experimental setup will be constructed with using of developed parts and units, the characteristics of this setup will be investigated at the neutron beam.
Foreign collaborators of the project are following: professor J. B. Forsyth (Rutherford Appleton Laboratory,ISISE, Didcot, UK) and Dr. O.Zimmer (Institute Laue- Langevin,Grenoble,France). On the basis of the scientific and technical results of the first part of the Project they strongly recomended its further funding.
There were permanent contacts with foreign collaborators. Professor J.B.Forsyth several times visited JINR and Neutron Laboratory where experimental facility is situated. Dr. O.Zimmer also visited Neutron Laboratory in JINR. There were fruitful scientific discussions during their visits. Besides there were the meetings of Dr. V.V.Novitsky and Dr.A.G.Beda with foreign collaborators during the international workshop in ILL (October, 1998) and meeting of Dr.Beda with professor J.B.Forsyth during the visit of Dr.Beda in RAL (april,1999) on invitation of professor J.B.Forsyth.
Duration of the second part of the Project - 18 months. Aggregated Personal Efforts of the second part is 263,5 work-months. Total Amount - 185000 $. In realization of the second part of the Project is supposed to use 15 specialists engaged in development WТ. Their part in the Aggregated Personal Efforts of the project will be about 60 %. All specialists will be engaged in the Project permanently.