Final-focus Superconducting Magnets for SuperKEKB

2014

Construction of the SuperKEKB has been progressed in KEK. The mechanical designs of the cryostats for the superconducting magnets in the interaction region are also being studied. In the cryostat designs, the mechanical strengths of the components were calculated, and the configurations of the cryostats were optimized. Because the vertical beam sizes need to be 50 nano-meter, vibration of the magnets due to the ground motion has been evaluated. We will present the cryostat designs and these vibration studies in this paper. INTRODUCTION Construction of the SuperKEKB has been progressed in KEK [1]. The target luminosity of the SuperKEKB is 8×10 cms, which is 40 times larger than the KEKB. The vertical beam sizes of electron and positron must be squeezed to the level of 50 nano-meter at the interaction point. The beam final focus system for the SuperKEKB consists of 4-superconducting (SC) quadrupole doublets, 43 SC-correctors, 4 SC-compensation solenoids [2]. Interaction region of the ...

Proceedings of the 2005 Particle Accelerator Conference

The Super-KEKB is the next generation collider for B factories, and its target luminosity is 4 10 35 cm-2 s-1. From the various points of view, the reality of this machine was discussed, and the magnet system in the interaction region has been also studied intensively. Especially, the study of the superconducting magnet system, which consists of the final focus quadrupoles and the compensation solenoids, has progressed. In this paper, the layout and the parameters of these superconducting magnets are reported.

IOP Conference Series: Materials Science and Engineering, 2019

The 55 SuperKEKB final focusing superconducting magnets are assembled into two cryostats, located at the left side and the right side of the accelerator interaction point, respectively. The two cryostats are cooled by sub-cooled liquid helium at 0.16 MPa with two independent refrigerators of about 250 W cooling capacity. From August 2016, the two cryostats were installed into the accelerator beam line and were connected with their own sub-coolers and refrigerators. As cryogenic systems, commissioning was carried out to cool down the cryostats, to excite superconducting magnets, and to test system interlock protections against some emergencies. This paper introduces the cryostats and cryogenic systems, and the commissioning processes. The cryostat heat loads were measured and the results are presented in this paper.

2014

A final focus magnet system of SuperKEKB consists of 4-superconducting (SC) quadrupole doublets, 43 SCcorrectors, 4 SC-compensation solenoids. They are aligned in a detector (Belle-II) solenoid which generates a longitudinal field of 1.5 T. These magnetic components are separately designed and the beam optics simulation has been performed with the linear-superposed-magnetic-field maps. Here, we combined these components into a magnetic-fieldanalysis model by using Opera3D/TOSCA and preliminary results of the field analysis are shown.

SuperKEKB is an upgrade project of KEKB to increase its luminosity to 8 x 1035 cm−2 s−1 based on the nano-beam scheme. In SuperKEKB, one of a key element is a final-focus system; it reduces e−/e+ beam size to 50 nm in vertical and 10 μm in horizontal direction at an interaction point (IP). The system consists of eight superconducting quadrupole magnets and four quadrupoles are aligned on the each beam line. The quadrupole, QC1P(QC1E), which is located at the closest position to the IP on the e+(e−) beam line, generates a field gradient of about 70 T/m. An inner diameter of coil and a magnetic length for QC1P(QC1E) are 25(33) mm and 334(373) mm, respectively. The production of all quadrupole magnets are completed. To confirm their field qualities, we performed magnetic measurement for each magnet in advance to be integrated into cryostats on the beam lines. In the measurement, the quadrupoles were cooled down to 4.2 K in a test vertical cryostat and magnetic field were measured with harmonic coils. The amplitudes of higher order harmonics for all magnets met requirements from beam optics design. In this paper we describe the measurement results.

2016

The Interaction Region (IR) quadrupoles for the SuperKEKB luminosity upgrade at KEK have multiple superconducting correction coils that are needed to fulfill performance goals. These correctors were produced at BNL and undergo system tests and measurement at KEK before final installation of the completed systems in the IR hall. Here we report on measurement results.

2013

SuperKEKB is an upgrade project underway at KEK, to increase the KEKB b-factory luminosity 40-fold by using nanobeam Interaction Region (IR) focusing optics [1] for which the production of new superconducting IR magnets and correctors is critical [2]. SuperKEKB corrector design and production is challenging since many different coils are needed for precise control of IR magnetic fields, in order to ensure good beam lifetime and there is very little space for them. SuperKEKB corrector production is about half completed and we report here on new techniques recently developed to address production challenges.

2013

Construction of the SuperKEKB accelerator started from 2010. The final focusing system in SuperKEKB was designed, and it consisted of 8 superconducting quadrupole magnets. As part of the R&D of the final focusing system, t wo prototype magnets were designed and constructed. The magnets were cooled to 4 K, and they were excited over the design current and the field measurements were performed.

IEEE Transactions on Appiled Superconductivity, 2003

The concept for GSI's planned future facility is based on two superconducting synchrotrons, SIS 100 and SIS 200. The two accelerators are in the same tunnel and have the same radius R, for operation at BR = 100 Tm and 200 Tm respectively. Superconducting magnets are necessary to reach the appropriate magnetic field and may considerably reduce the investment and operating costs, in comparison with conventional magnets. An R&D program was initiated to develop dipole magnets with maximum fields of 2 and 4 Tesla and dipole ramp rates of 4 T/s and 1 T/s, respectively. These requirements were chosen to achieve high average beam intensities. The SIS 100 dipole is a window-frame Nuclotron-type dipole and is being developed in collaboration with JINR (Dubna, Russia). This magnet has been operated at 4 T/s up to a field of 2 Tesla. Reduced losses and improved magnetic field quality are required for the SIS 100 accelerator. In a separate collaboration with BNL (Upton, USA), the one coil layer cos θ-type RHIC arc dipole, originally designed for operation at 3.5 Tesla with a rather slow ramp rate of 0.042 T/s, will be upgraded for the SIS 200 accelerator to operate at a ramp rate of 1 T/s, up to a field of 4 T. R&D for a 6 Tesla dipole was started in collaboration with IHEP (Protvino, Russia), to further increase the rigidity of the SIS 200 ring to 300 Tm. Alternative schemes have been investigated. Besides the synchrotrons, the planned facility will consist of several storage rings and the Super Fragment Separator (SFRS), which have mainly DC magnets with large apertures. NSCL (East Lansing, USA) prepared a feasibility study for these superconducting magnets. The main results of the R&D are presented.

2012

The SuperKEKB is now in a construction stage. The injector linac should be upgraded for realizing the 40times higher luminosity than that of KEKB. This requires both bunch charge increase and reduction of beam emittance. All of the relevant hardware designs for the injector system are being finalized now to meet the commissioning of the ring by the end of 2014. In the present paper is briefly reviewed the overall progress of such design decisions and hardware developments in the last two years. A perspective towards the commissioning is also presented.