Present Status of RCNP-Ring Cyclotron Facilities
-Reference for Proposals-
- This is a report of the RCNP-Ring Cyclotron and its experimental equipments. The
- Research Center for Nuclear Physics (RCNP) is a national nuclear physics laboratory
- with the Ring cyclotron and the AVF cyclotron. The Ring cyclotron is in full operation
- and the intermediate-energy nuclear physics programs are in progress at its center.
- We hope that this report will be useful to write experimental proposals.
A. Present status of beam
- The type and quality of beams accelerated with the Ring cyclotron are listed in the following.
- Proton
- (Unpol)
- (Pol.70%)
400-500psec
- Deuteron
- (Unpol)
- (Pol.70%)
- This is a summary of the experimental facilities. Usere are encouraged to contact the following persons for technical details.
| [1]High-resolution spectrometer ; Grand Raiden (WS-course) | ||
| Yasuhiro Sakemi | +81-6-879-8934 | sakemi@rcnp.osaka-u.ac.jp |
| [2]Large acceptance spectrometer (WS-course) | ||
| Yasuhiro Sakemi | +81-6-879-8934 | sakemi@rcnp.osaka-u.ac.jp |
| [3]Neutron-TOF facility (N0-course) | ||
| KIchiji Hatanaka | +81-6-879-8928 | hatanaka@rcnp.osaka-u.ac.jp |
| [4]Heavy-ion secondary-beam course (EN-course) | ||
| Tadashi Shimoda | +81-6-850-5744 | shimoda@rcnp.osaka-u.ac.jp |
| [5]General purpose scattering chamber (ES-course) | ||
| KIchiji Hatanaka | +81-6-879-8928 | hatanaka@rcnp.osaka-u.ac.jp |
| [6]On-line computing facilities | ||
| Yasuhiro Sakemi | +81-6-879-8934 | sakemi@rcnp.osaka-u.ac.jp |
| [7]Off-line computing facilities | ||
| Atsushi Hosaka | +81-6-879-8934 | hosaka@rcnp.osaka-u.ac.jp |
[1] High-resolution spectrometer: Grand Raiden (WS-course)
The maximum magnetic rigidity is B_rho=5.66 Tm, and the momentum range is 5%. The maximum solid angle is 5.6 msr (design value), +- 20 mr for the horizontal acceptance angle and +- 70 mr for the vertical acceptance angle. There are two vertical drift chambers (effective length 1.2 m ) for general use as the focal plane position counters of the spectrometer. The position and angular resolution obtained from ray-tracing are 0.2 mm and 2.0 mr, respectively. It is possible to measure angular distributions of scattered particles from -5 deg to 90 deg. We have succeeded to measure 12C(p,p') at zero degrees by decreasing the beam halo. By using dispersion matching techniques we obtained an energy resolution of 20 keV for 300 MeV and 400 MeV protons. We are developing experimental procedures and beam tuning techniques to perform high resolution measurements in a simpler way. In the scattering chamber there are three remote driving systems, target (up and down), a turntable with Faraday cup, and one general purpose turntable. Focal Plane Polarimeter (FPP) and a Dipole magnet for Spin Rotation (DSR) are installed to measure polarization transfer coefficients. Users are strongly encouraged to collaborate with the development group when performing an experiment with the FPP system.
[2] Large acceptance spectrograph (WS-course)
- The maximum magnetic rigidity is B_rho=3.2 Tm and the momentum acceptance is 30%. The maximum solid angle is about 20 msr, +- 60 mr in the horizontal and +- 100 mr for the vertical plane. It is possible to measure angular distributions of scattered particles from -10 to 125 degrees. At forward angles, smaller than 25 degrees, the incident beam should be stopped at the Faraday cup inside the scattering chamber. The focal plane counter system consists of two vertical drift chambers (effective length: 1.7 m, effective height: 35 cm ) for ray-tracing and two planes of plastic scintillators for the trigger (200cm x 45cm, 6 mm thickness). In addition, twelve segmented scintillators (hodoscopes) are available for the measurement of 2He or other two particles in coincidence.
- The parameters for trace-back have been established. It is possible to measure and analyze with a momentum resolution of 5x10-4 (including momentum width of beam), and angular resolution (FWHM) of 2 mr horizontally and 30 mr vertically. In the zero-degrees measurements, if the momentum of the measured particle is about half of the incident beam momentum, we can transport the incident beam through the spectrograph and stop in an external beam dump.
[3] Neutron-TOF facility (N0-course)
The length of the neutron flight path is 100 m at maximum and 10 m at minimum. Neutrons can be measured under the following conditions: 100 m flight path, 1/9 beam pulsing, and 50-60 MeV neutron detection threshold. The neutron detectors (neutron polarimeter) consist of four liquid scintillators (BC519, 1x1 m2, 10 cm thick), two plastic scintillators (BC408, 1x1 m2, 10 cm thick), and ten plastic hodoscopes (1m x 10 cm, 5cm thick). A spin rotation magnet, NSR, is used to measure neutron polarization in the scattering plane.
There are two beam polarimeters and a scattering chamber for coincidence measurement (40 cm diameter) upstream from the swinger magnet. In the scattering chamber there are three remotely controlled driving systems, one for the target (up and down) and two general purpose turntables. Using these systems, it is possible to perform coincidence measurements of particles with neutrons at zero degrees. However, the background in the experimental hall has not yet been examined.
The present status is summarized as follows:
- Beam pulsing is available up to 1/9.
- The phase width of the beam is about 0.4 nsec (FWHM). Full phase width including resolutions of detectors and electric circuits is 1 nsec (FWHM). This phase width corresponds to an energy resolution of 1% for a flight path of 60 m.
- Single turn extraction from the Ring cyclotron is available.
- Backgrounds from the swinger magnet, from the walls of the TOF tunnel and so on are observed to be negligibly small.
[4] Heavy-ion secondary-beam course (EN-course)
The secondary-beam course is a fragment separator for intermediate energy heavy-ion reactions. It consists of two dipole magnet systems and an energy degrader in-between. The reaction products at the first target point are isotopically separated and achromatically focused at the second target point. The primary beam can be injected onto the first target with a tilt angle of up to 8 degrees and thus spin-polarized secondary beams can be produced. The maximum magnetic rigidity of course is B_rho=3.2 Tm. The momentum acceptance is 4 %, and the angular acceptance is +- 20 mr in the horizontal plane and +- 14 mr in the vertical plane. The beam spot-size at the second target point is about 6.5 mm (horizontal) and 2 mm (vertical) in FWHM.
The development of the secondary-beam course has been completed using primary 14N beams of 40 and 70 MeV/u. The reaction products of 12B and 8Li have been successfully separated with an isotopic purity better than 99%. A typical intensity of 12B was 2000 pps with the primary-beam intensity of 30 enA.
[5]General purpose scattering chamber(ES-course)
- A general purpose scattering chamber is available at the ES-course. The outer diameter of the chamber is 800 mm and there are vacuum windows in the horizontal plane. Charged particles can be measured out of the chamber in the angular range from 15 to 110 degrees in both sides of the beam.
- The available beam current is limited to 10nA for 400MeV protons from the radiation safety point of view.
- There is a beam irradiation system for biological studies. It consists of wabbler magnets, beam scatterers, range shifters and range modulators. The maximum size of the irradiation field is 50mm in diameter. The sample changer is remote controlled.
[6] On-line computing facilities
- The data from FERA (ADC/TDC), LeCroy 3377 (VDC), LeCroy PcosIII (MWPC) etc, are stored in high speed memories (HSM 8170) and/or dual port memories (LeCroy 1191).
- They are transfered to a computer (SUN SP/20) through optically-linked reflective memory modules for experiments in WS, whereas they are transfered to a host computer (Linux-PC) through a optically-linked PCI-VME interface (SBS 617 system) for experiments in N0.
- For experiments in WS, the data are re-transfered to a host computer (IBM-AIX) for the data storage and the online analysis.
- The data can be stored in the local hard disks of the host computers, and their storage sizes are 150 GB and 100 GB for IBM-AIX and Linux-PC, respectively.
- All of the data should subsequently be transfered to mass storage devices, work disks of the main computing facility, DLT, DAT, and so on.
- Several online monitor systems based on the CERN libraries (HBOOK and PAW) are available for experiments in WS.
- A online monitor system based on the HANDYPAK is also available for experiments in WS and N0.
- Details for the DAQ and online-monitor systems are described in the following URL:
- http://www.rcnp.osaka-u.ac.jp/Divisions/np1-a/daq.html
- Users who are not familiar with each system are encouraged to contact the person in charge of each apparatus.
- [7] Off-line computing facilities
- Off-line computer systems use an IBM RS/6000SP computer.
- It has a large amount of storage region of 38 TB hard disk.
- The computer systems are connected through campus network (ODINS) to the world wide network HEPNET and INTERNET.
- The general purpose computer system was replaced in December 2000.