2000 Fiscal Year Final Research Report Summary
Study on beam instabilities at electron-positron colliders (factories)
| Project/Area Number |
10440081
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | KEK, High Energy Accelerator Research Organization |
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Principal Investigator |
KUROKAWA Shin-ichi High Energy Accelerator Research Organization, Accelerator Lab., Professor, 加速器研究施設, 教授 (90044776)
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| Co-Investigator(Kenkyū-buntansha) |
ISAWA Masaaki High Energy Accelerator Research Organization, Accelerator Lab., Professor, 物質構造科学研究所, 教授 (10168164)
KATOH Tadahiko High Energy Accelerator Research Organization, Accelerator Lab., Professor, 加速器研究施設, 教授 (10044752)
KASUGA Toshio High Energy Accelerator Research Organization, Photon Factory, Professor, 物質構造科学研究所, 教授 (70044758)
KATO Shigeki High Energy Accelerator Research Organization, Accelerator Lab., Associate Professor, 加速器研究施設, 助教授 (60259984)
FUKUMA Hitoshi High Energy Accelerator Research Organization, Accelerator Lab., Associate Professor, 加速器研究施設, 助教授 (40150007)
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| Project Period (FY) |
1998 – 2000
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| Keywords | beam instability / electron cloud instability / fast ion instability / electron-positron collider / B-factory / solenoid |
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| Research Abstract |
Study of fast-ion instability (FII) and electron cloud instability (ECI), which are most serious instabilities at high-performance, two-ring electron-positron colliders (factories) were investigate by using KEKB at KEK and BEPC at IHEP Beijing.
In an electron ring, the growth of vertical dipole oscillation amplitued along a bunch train was observed by the use of a transient recorder. Since the oscillation frequencies coincided with those of ion oscillations, we believe that FII was detected.
In a positron ring, not only dipole oscillations but also vertical beam blowup were observed. We measured the tune of each bunch along a bunch train and found that the tune increased along the train and became saturated at some value and that the increase of the tune was proportional to the line charge density of the bunch train. This strongly suggests that electron clouds around the beam excited intra-bunch oscillation and caused the beam blowup.
In JFY2000 we wound solenoids over the KEKB positron ring over 1200 m. These solenoids clearly suppressed the beamblowup ; however, the suppression was not as strong as simulations predicted. The reason yet to be made clear. By continued operation of KEKB with these solenoids on, the beam blowup has become weaker. By the end of March 2001, we got a luminoity of 3.2×10^<33>cm^<-2>s^<-1>, which is close to the world record of 3.3×10^<33>cm^<-2>s^<-1> recorded at PEP-II.Some scrubbing effect is suspected.
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