Project of VEPP-2000 electron-positron collider
The status of VEPP-2M collider is presented. Implementation of Round Colliding Beams (RCB) concept in the new collider VEPP-2M is outlined, potential advantages of RCB over the flat colliding beams are discussed. The main desing parameters and features of this VEPP-2000 collider are reported.
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| Дата: | 2001 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
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| Цитувати: | Project of VEPP-2000 electron-positron collider / Yu.M. Shatunov, A.V. Evstigneev, D.I. Ganyushin, P.M. Ivanov, I.A. Koop, V.S. Kuzminykh, A.P. Lysenko, N.A. Mezentsev, N.V. Mityanina, I.N. Nesterenko, A.V. Otboev, E.A. Perevedentsev, V.M. Petrov, D.B. Schwartz, P.Yu. Shatunov, A.N. Skrinsky, A.A. Valishev, V.N. Volkov // Вопросы атомной науки и техники. — 2001. — № 3. — С. 6-8. — Бібліогр.: 6 назв. — англ. |
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irk-123456789-792112015-03-30T03:01:56Z Project of VEPP-2000 electron-positron collider Shatunov, Yu.M. Evstigneev, A.V. Ganyushin, D.I. Ivanov, P.M. Koop, I.A. Kuzminykh, V.S. Lysenko, A.P. Mezentsev, N.A. Mityanina, N.V. Nesterenko, I.N. Otboev, A.V. Perevedentsev, E.A. Petrov, V.M. Schwartz, D.B. Shatunov, P.Yu. Skrinsky, A.N. Valishev, A.A. Volkov, V.N. The status of VEPP-2M collider is presented. Implementation of Round Colliding Beams (RCB) concept in the new collider VEPP-2M is outlined, potential advantages of RCB over the flat colliding beams are discussed. The main desing parameters and features of this VEPP-2000 collider are reported. 2001 Article Project of VEPP-2000 electron-positron collider / Yu.M. Shatunov, A.V. Evstigneev, D.I. Ganyushin, P.M. Ivanov, I.A. Koop, V.S. Kuzminykh, A.P. Lysenko, N.A. Mezentsev, N.V. Mityanina, I.N. Nesterenko, A.V. Otboev, E.A. Perevedentsev, V.M. Petrov, D.B. Schwartz, P.Yu. Shatunov, A.N. Skrinsky, A.A. Valishev, V.N. Volkov // Вопросы атомной науки и техники. — 2001. — № 3. — С. 6-8. — Бібліогр.: 6 назв. — англ. 1562-6016 PACS number: 29.17.+w http://dspace.nbuv.gov.ua/handle/123456789/79211 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
| language |
English |
| description |
The status of VEPP-2M collider is presented. Implementation of Round Colliding Beams (RCB) concept in the new collider VEPP-2M is outlined, potential advantages of RCB over the flat colliding beams are discussed. The main desing parameters and features of this VEPP-2000 collider are reported. |
| format |
Article |
| author |
Shatunov, Yu.M. Evstigneev, A.V. Ganyushin, D.I. Ivanov, P.M. Koop, I.A. Kuzminykh, V.S. Lysenko, A.P. Mezentsev, N.A. Mityanina, N.V. Nesterenko, I.N. Otboev, A.V. Perevedentsev, E.A. Petrov, V.M. Schwartz, D.B. Shatunov, P.Yu. Skrinsky, A.N. Valishev, A.A. Volkov, V.N. |
| spellingShingle |
Shatunov, Yu.M. Evstigneev, A.V. Ganyushin, D.I. Ivanov, P.M. Koop, I.A. Kuzminykh, V.S. Lysenko, A.P. Mezentsev, N.A. Mityanina, N.V. Nesterenko, I.N. Otboev, A.V. Perevedentsev, E.A. Petrov, V.M. Schwartz, D.B. Shatunov, P.Yu. Skrinsky, A.N. Valishev, A.A. Volkov, V.N. Project of VEPP-2000 electron-positron collider Вопросы атомной науки и техники |
| author_facet |
Shatunov, Yu.M. Evstigneev, A.V. Ganyushin, D.I. Ivanov, P.M. Koop, I.A. Kuzminykh, V.S. Lysenko, A.P. Mezentsev, N.A. Mityanina, N.V. Nesterenko, I.N. Otboev, A.V. Perevedentsev, E.A. Petrov, V.M. Schwartz, D.B. Shatunov, P.Yu. Skrinsky, A.N. Valishev, A.A. Volkov, V.N. |
| author_sort |
Shatunov, Yu.M. |
| title |
Project of VEPP-2000 electron-positron collider |
| title_short |
Project of VEPP-2000 electron-positron collider |
| title_full |
Project of VEPP-2000 electron-positron collider |
| title_fullStr |
Project of VEPP-2000 electron-positron collider |
| title_full_unstemmed |
Project of VEPP-2000 electron-positron collider |
| title_sort |
project of vepp-2000 electron-positron collider |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2001 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/79211 |
| citation_txt |
Project of VEPP-2000 electron-positron collider / Yu.M. Shatunov, A.V. Evstigneev, D.I. Ganyushin, P.M. Ivanov, I.A. Koop, V.S. Kuzminykh, A.P. Lysenko, N.A. Mezentsev, N.V. Mityanina, I.N. Nesterenko, A.V. Otboev, E.A. Perevedentsev, V.M. Petrov, D.B. Schwartz, P.Yu. Shatunov, A.N. Skrinsky, A.A. Valishev, V.N. Volkov // Вопросы атомной науки и техники. — 2001. — № 3. — С. 6-8. — Бібліогр.: 6 назв. — англ. |
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Вопросы атомной науки и техники |
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PROJECT OF VEPP-2000 ELECTRON-POSITRON COLLIDER
Yu.M. Shatunov, A.V. Evstigneev, D.I. Ganyushin, P.M. Ivanov, I.A. Koop,
V.S. Kuzminykh, A.P. Lysenko, N.A. Mezentsev, N.V. Mityanina, I.N. Nesterenko,
A.V. Otboev, E.A. Perevedentsev, V.M. Petrov, D.B. Schwartz, P.Yu. Shatunov, A.N. Skrinsky,
A.A. Valishev, V.N. Volkov
Budker Institute of Nuclear Physics, Novosibirsk, 630090, Russia
The status of VEPP-2M collider is presented. Implementation of Round Colliding Beams (RCB) concept in the new
collider VEPP-2000 is outlined, potential advantages of RCB over the flat colliding beams are discussed. The main
design parameters and features of this VEPP-2000 collider are reported.
PACS numbers: 29.17.+w
1 STATUS OF VEPP-2M AND MOTIVA-
TION FOR THE CONSTRUCTION OF A
NEW COLLIDER
Since the end of 1992 the e e+ − collider VEPP-2M
in Novosibirsk has been successfully running in the c.m.
energy range from the threshold of hadron production
up to 1.4 GeV. Since 1984 VEPP-2M is operating with
the five-pole superconducting wiggler with the maxi-
mum field 8B T= , which increases the beam emit-
tance by a factor of 3. The integrated luminosity of
about 50 pb-1 as collected with two modern detectors
SND [1] and CMD-2[2] allowing precise measurements
of most of the hadronic channels of e e+ − annihilation.
Together with 24 pb-1 collected at VEPP-2M in the pre-
vious generation of experiments in 1974–1987, this in-
tegrated luminosity is more than one order of magnitude
higher than about 6 pb-1 accumulated by various experi-
mental groups in Frascati and Orsay in the c.m. energy
range from 1.4 to 2 GeV. Thus, there is a serious energy
gap between the maximum energy attainable at
VEPP-2M and 2 GeV in which existing data on e e+ −
annihilation into hadrons are rather imprecise. Accurate
measurements of hadronic cross sections in this energy
range are crucial for better understanding of many phe-
nomena in high energy physics.
A recent decision to upgrade the VEPP-2M complex
by replacing the existing collider with a new one, in or-
der to improve the luminosity and at the same time in-
crease the maximum attainable energy up to 2 GeV, will
significantly broaden the potential of experiments per-
formed at the collider. Following modern trends, the
new project was named VEPP-2000.
2 ROUND COLLIDING BEAMS
During the last decade at BINP the concept of
Round Colliding Beams (RCB) [3] was proposed.
The evident advantage of round colliding beams is
that with the fixed particle density, the tune shift from
the opposite bunch becomes twice as small as the tune
shift in the case of flat colliding beams. Besides, the lin-
ear beam-beam tune shift in the round beams becomes
independent on the longitudinal position in the bunch,
thereby weakening the action of synchro-betatron reso-
nances.
The main feature of the RCB is rotational symmetry
of the kick from the round opposite beam; complement-
ed with the X-Z symmetry of the betatron transfer ma-
trix between the collisions, it results in conservation of
particle angular momentum. Thus, the transverse mo-
tion becomes equivalent to a one-dimensional (1D) mo-
tion. Resulting elimination of all the betatron coupling
resonances is of crucial importance, since they are be-
lieved to cause the beam lifetime degradation and blow-
up.
The above arguments in favour of RCB have been
checked out by the computer simulations of the beam-
beam effects in RCB option [4]. The simulations have
also demonstrated stability of RCB against the “flip-
flop” effect, similarly to conclusions from simple flip-
flop models [5].
3 VEPP-2000 PROJECT
3.1 Collider Optics
Our approach to the new collider optics is based on
the idea of round colliding beams [3]. The main princi-
ples of round beam mode will be satisfied by placing
SC solenoids in two Interaction Regions equipped with
existing particle detectors (Fig. 1).
Fig. 1. The VEPP-2000 collider layout.
The superconducting solenoids will provide equal
*β -functions and rotate by 2/π the planes of betatron
oscillations. This will result in alternation of vertical
and horizontal orientations of the planar betatron eigen-
modes over each half-turn, which in turn will lead to
their equal tunes and emittances. The optical functions
of the round beam lattice are presented in Fig. 2.
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №3.
Серия: Ядерно-физические исследования (38), с. 6-8.
6
Fig. 2. Half period lattice functions. S=0 corre-
sponds to IP.
An essential advantage of the found optics is zero
dispersion in the IRs, RF cavity, and injection straight
sections.
The chosen optics has another very useful feature.
Variation of the focusing strength of the solenoids
changes *β and the beam emittance in inverse propor-
tion, at a fixed energy. Changing the energy, we can
squeeze *β , conserving the maximum beam size at the
solenoids, thus giving a possibility to tune optics for
better performance. Apparently, this feature provides
the luminosity scaling at lower energies approximately
as 2γ (instead of 4γ for the option with fixed *β ).
The main parameters of the new collider are given in
Table 1.
3.2 Injection
The injection of beams into the storage ring is
planned to be done in the horizontal plane into the long
drift opposite to the RF cavity. The inflector plates will
be placed on the inner side of the vacuum chamber in
the bending magnets at the ends of the drift. The advan-
tage of such a scheme is independence of the injected
beam trajectory on the solenoids field. This gives us an
opportunity to test different options of optics: usual
round beams, “Mobius”, and flat beams with zero rota-
tion of the betatron oscillation plane.
The BEP booster is capable of production beams
with the energy of up to 900 MeV. Thus, operation at
lower energies will be continuous, with injection of the
beam at the experiment energy. In the range from
900 MeV to 1 GeV the energy ranging from 900 MeV
to the experiment energy is required.
3.3 Chromaticity correction
The chromaticity correction is performed by the sex-
tupole families Sx and Sz, placed near the quadrupoles
of triplets, where the dispersion function is non-zero.
Another variant discussed implies a special correction
of pole profiles of the horizontally focusing quadrupoles
in the triplets.
Table 1. Main parameters of the collider at E=900 MeV
Circumference, m C 24.388
RF frequency, MHz
0f 172.0
RF voltage, kV V 100
RF harmonic number q 14
Momentum compaction α 0.036
Synchrotrone tune sν 0.003
Emittances, cm ⋅ rad xε
zε
52.2 10−⋅
52.2 10−⋅
Energy loss/turn, keV 0E∆ 41.5
Dimensionless
damping
decrements
zδ
xδ
sδ
52.3 10−⋅
52.3 10−⋅
54.6 10−⋅
Energy spread εσ 46.4 10−⋅
xβ at IP, cm
zβ at IP, cm
xβ
zβ
6.3
6.3
Betatron tunes ,x zν ν 4.1, 2.1
Particles/bunch ,e e− + 111.0 10⋅
Bunches/beam 1
Tune shifts xξ
zξ
0.075
0.075
Luminosity/IP, cm-2 ⋅ s-1
maxL 321.0 10−⋅
The scheme with only two sextupole families leaves
the problem of dynamical aperture unresolved, this
forces us to use an additional sextupole correction fami-
ly to control the sextupole perturbation harmonics.
These sextupoles are placed in dispersion-free regions:
in the injection and RF cavity drifts, between the bend-
ing magnets and quadrupoles. Application of these cor-
rectors yields dynamical aperture of about σ14 (17mm
inside the solenoid) which is still less than mechanical
aperture. So, search for a better solution is in progress.
4 TECHNICAL FEATURES
4.1 Superconducting Solenoids
Focusing in the two interaction regions is performed
by SC solenoids, installed symmetrically with respect to
the IPs. Each solenoidal block consists of a main
solenoid which is longitudinally divided into two parts,
and a compensating solenoid with reverse field to adjust
longitudinal field integral and focussing. Such a scheme
gives an additional possibility to control the *β value
by feeding only one half of the main solenoid at lower
energies.
The solenoid coil is divided into three sections: in-
ner section has thickness 30 mm and is made of
SnNb3 wire 1.23 mm in diameter (50% Cu + 50%
SnNb3 ); middle section has thickness 20 mm and is
wound with a NbTi wire 1.2 mm in diameter (48%Cu
+52% NbTi ) and outer layer has thickness of 10 mm,
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №3.
Серия: Ядерно-физические исследования (38), с. 7-8.
7
made of NbTi wire 0.85 mm in diameter (48% Cu
+52% NbTi ). To feed this three-section coil we plan to
use two power supply units. Connection scheme implies
that the current in the outer section is the sum of cur-
rents in the inner ones. The distribution of currents in
the sections is: inner section - 145 A, intermediate sec-
tion - 167 A, outer section - 312 A. The peak magnetic
field is 12.1 T.
Magnetic flux is closed by the iron return yoke lo-
cated together with all the coils in a common LHe cryo-
stat. Aperture of the coil is 50.0 mm. The inner tube of
the helium vessel is a part of the collider vacuum cham-
ber. A nitrogen vapour cooled liner is envisaged to pro-
tect the surface of the helium cryostat from heating by
synchrotron radiation.
4.2 Dipole Magnets, Quadrupoles and Sextupoles
Constrained VEPP-2M complex area restricts the
machine dimensions leading to necessity of using strong
dipole magnets. To achieve the beam energy of 1 GeV
guiding field of 2.4 T is required. The design of the
BEP booster ring magnet [6] which works at this field
level is intended to be used. Magnet bending radius is
1400 mm, the gap is 40 mm. Number of coil turns is 10.
At maximum current 9.5 kA the power consumption is
100 kW/magnet.
New lattice will include 5 families of quadrupoles
with maximum gradient of 50 T/m and 3 families of
sextupoles. Inscribed circle diameter of quadrupoles and
sextupoles is 40 mm. Chromaticity correction sex-
tupoles (two families) are located between quadrupoles
of the triplets. Similar 5 kW power supply units will be
used to feed the coils in the quadrupole magnets and in
the sextupoles. All other low-current coils of the closed
orbit steering and gradient correction coils in the
quadrupole magnets will be powered using existing
power supplies.
4.3 RF System
Beam revolution frequency is 12.292 MHz. The ac-
celerating RF frequency was chosen at 14-th revolution
frequency harmonic i.e. 172 MHz. With accelerating
voltage of 100 kV the bunch length is about σ = 3 cm at
the energy of 1 GeV. Energy loss per turn is 64 keV,
and with colliding beam currents of 1.02 × A the pow-
er delivered to the beams is 12.8 kW. The so-called sin-
gle-mode cavity is proposed to be used to ease suppres-
sion of coherent instabilities, see Fig. 3. Two coaxial
damping loads are foreseen to absorb the energy from
high-order modes excitation. The fundamental mode is
isolated from the upper load by the tunable choke.
Fig. 3. Cross-section of the cavity. The locations
of HOM.
4.4 Vacuum System
High vacuum pumping of the experimantal straight
sections will be performed by the internal tube of the
LHe vessel. For this purpose it is planned to make slits
in the nitrogen cooled liner which protects the LHe sur-
face from heating by the synchrotron radiation. In the
rest regions combined ion-pumping and getter pumping
are intended to be used. Average vacuum in the ring at
the working currents should be higher than 810− torr.
5 CONCLUSION
− Experimental testing of RCB at VEPP-2000 should
verify predictions on extremely high attainable
space charge parameters for the round beams.
− The machine tune-up procedures will be worked
out for implementation of such a non-conventional
optics.
− The efforts and expenses needed to build
VEPP-2000 are moderate and so this work can be
carried out within the next year.
REFERENCES
1. M.N.Achasov et al., Preprint BudkerINP 98-65,
Novosibirsk, 1998.
2. R.R.Akhmetshin et al., Preprint BudkerINP 99-11,
Novosibirsk, 1999.
3. V.V.Danilov et al., “The Concept of Round Collid-
ing Beams” // Proc. EPAC'96, Barcelona, 1996,
p.1149.
4. A.N.Filippov et al.// Proc. 15th Int. Conf. High En-
ergy Accelerators, Hamburg (Germany), 1992,
p.1145.
5. A.V.Otboyev and E.A.Perevedentsev // Proc. 1999
PAC, New York (1999).
6. V.V.Anashin et al., Preprint BudkerINP 84-114,
Novosibirsk, 1984.
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №3.
Серия: Ядерно-физические исследования (38), с. 8-8
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