-
H. Ishino,
R. Abe,
T. Abe,
H. Aihara,
Y. Asano,
T. Aso,
A. Bakich,
T. Browder,
M.C. Chang,
Y. Chao, [......],
Y. Yamada,
H. Yamamoto,
Y. Yamashita,
M. Yamauchi,
H. Yanai,
R. Yang,
Y. Yasu,
M. Yokoyama,
T. Ziegler,
D. Zontar
[show abstract]
[hide abstract]
ABSTRACT: A newly developed data acquisition system (DAQ) for the upgraded silicon vertex detector (SVD2) in the Belle experiment is described. The system consists of 12 PCs connected through PCI I/O boards to 36 flash analog-to-digital converters (FADCs) to read out a system comprising a total of 110 592 strips. It is designed to cope with the increased number of readout channels and the maximum trigger rate of 1 kHz, foreseen in the future operation with higher beam currents. A measurement of the system performance using sparsification algorithm we have developed yields a 1.3-kHz readout rate for a 5% occupancy with less than 5% dead time, which satisfies the requirements on the maximum trigger rate.
IEEE Transactions on Nuclear Science 11/2004; · 1.45 Impact Factor
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Y Chao,
P Chang,
K Abe,
N Abe,
I Adachi,
H Aihara,
K Akai,
M Akatsu,
M Akemoto,
Y Asano, [......],
S L Zang,
C C Zhang,
J Zhang,
L M Zhang,
Z P Zhang,
Y Zheng,
V Zhilich,
T Ziegler,
D Zontar,
D Zürcher
[show abstract]
[hide abstract]
ABSTRACT: We report evidence for direct CP violation in the decay B0-->K+pi(-) with 253 fb(-1) of data collected with the Belle detector at the KEKB e(+)e(-) collider. Using 275x10(6) BB pairs we observe a B-->K+/-pi(-/+) signal with 2140+/-53 events. The measured CP violating asymmetry is A(CP)(K+pi(-))=-0.101+/-0.025(stat)+/-0.005(syst), corresponding to a significance of 3.9sigma including systematics. We also search for CP violation in the decays B+-->K+pi(0) and B+-->pi(+)pi(0). The measured CP violating asymmetries are A(CP)(K+pi(0))=0.04+/-0.05(stat)+/-0.02(syst) and A(CP)(pi(+)pi(0))=-0.02+/-0.10(stat)+/-0.01(syst), corresponding to the intervals -0.05<A(CP)(K+pi(0))<0.13 and -0.18<A(CP)(pi(+)pi(0))<0.14 at 90% confidence level.
Physical Review Letters 11/2004; 93(19):191802. · 7.37 Impact Factor
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T. Ziegler,
R. Abe,
T. Abe,
H. Aihara,
Y. Asano,
T. Aso,
A. Bakich,
T. Browder,
M.C. Chang,
Y. Chao, [......],
Y. Watanabe,
Y. Yamada,
H. Yamamoto,
Y. Yamashita,
M. Yamauchi,
H. Yanai,
R. Yang,
Y. Yasu,
M. Yokoyama,
Zontar
[show abstract]
[hide abstract]
ABSTRACT: During the summer shutdown of 2003, the new silicon vertex detector SVD2 was installed in Belle at the KEKB factory and started to take data in October 2003. It provides important improvements in the tracking capabilities and adds new trigger functionality. In addition, a new hardware trigger Level 1.5 was designed and installed that takes advantage of the digitized SVD hit data. The improvement in the Belle trigger system will be important to deal with the increasing luminosity and higher beam currents of the KEKB factory.
IEEE Transactions on Nuclear Science 09/2004; · 1.45 Impact Factor
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K. Abe,
N. Abe,
T. Abe,
I. Adachi,
H. Aihara,
K. Akai,
M. Akatsu,
M. Akemoto,
Y. Asano,
T. Aushev, [......],
A. Yamaguchi,
H. Yamamoto,
Y. Yamashita,
M. Yamauchi,
M. Yokoyama,
M. Yoshida,
C. C. Zhang,
Z. P. Zhang,
V. Zhilich,
D. Žontar
[show abstract]
[hide abstract]
ABSTRACT: We present an improved measurement of CP-violating asymmetries in B0→π+π- decays based on a 78fb-1 data sample collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We reconstruct one neutral B meson as a B0→π+π- CP eigenstate and identify the flavor of the accompanying B meson from inclusive properties of its decay products. We apply an unbinned maximum likelihood fit to the distribution of the time intervals between the two B meson decay points. The fit yields the CP-violating asymmetry amplitudes Aππ=+0.77±0.27(stat)±0.08(syst) and Sππ=-1.23±0.41(stat)-0.07+0.08(syst), where the statistical uncertainties are determined from the Monte Carlo pseudoexperiments. We obtain confidence intervals for CP-violating asymmetry parameters Aππ and Sππ based on a frequentist approach. We rule out the CP-conserving case, Aππ=Sππ=0, at the 99.93% confidence level. We discuss how these results constrain the value of the Cabibbo-Kobayashi-Maskawa (CKM) angle φ2.
Phys. Rev. D. 07/2003; 68(1).
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J Kaneko,
K Abe,
T Abe,
I Adachi,
Byoung Sup Ahn,
H Aihara,
M Akatsu,
Y Asano,
T Aso,
V Aulchenko, [......],
J Yashima,
M Yokoyama,
Y Yuan,
Y Yusa,
C C Zhang,
J Zhang,
Z P Zhang,
Y Zheng,
V Zhilich,
D Zontar
[show abstract]
[hide abstract]
ABSTRACT: We report the first measurement of the branching fraction for the inclusive decay B-->X(s)l(+)l(-), where l is either an electron or a muon, and X(s) is a hadronic recoil system that contains an s quark. We analyzed a data sample of 65.4 x 10(6) B meson pairs collected with the Belle detector at the KEKB e(+)e(-) asymmetric-energy collider. We find B(B-->X(s)l(+)l(-))=[6.1 +/-1.4(stat) +1.4-1.1(syst)] x 10(-6) for dilepton masses greater than 0.2 GeV/c(2).
Physical Review Letters 01/2003; 90(2):021801. · 7.37 Impact Factor
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K Hara,
M Hazumi,
K Abe,
T Abe,
I Adachi,
Byoung Sup Ahn,
H Aihara,
M Akatsu,
Y Asano,
T Aso, [......],
A Yamaguchi,
Y Yamashita,
M Yamauchi,
H Yanai,
M Yokoyama,
Y Yuan,
Y Yusa,
Z P Zhang,
V Zhilich,
D Zontar
[show abstract]
[hide abstract]
ABSTRACT: We present a measurement of the B0-Bmacr;(0) mixing parameter Deltam(d) using neutral B meson pairs in a 29.1 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We exclusively reconstruct one neutral B meson in the semileptonic B0-->D(*-)l(+)nu decay mode and identify the flavor of the accompanying B meson from its decay products. From the distribution of the time intervals between the two flavor-tagged B meson decay points, we obtain Deltam(d)=(0.494+/-0.012+/-0.015) ps(-1), where the first error is statistical and the second error is systematic.
Physical Review Letters 12/2002; 89(25):251803. · 7.37 Impact Factor
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P Krokovny,
K Abe,
T Abe,
I Adachi,
Byoung Sup Ahn,
H Aihara,
M Akatsu,
Y Asano,
T Aso,
V Aulchenko, [......],
H Yanai,
J Yashima,
Y Yuan,
Y Yusa,
C C Zhang,
J Zhang,
Z P Zhang,
Y Zheng,
V Zhilich,
D Zontar
[show abstract]
[hide abstract]
ABSTRACT: We report the first observation of a B meson decay that is not accessible by a direct spectator process. The channel B(0)-->D(+)(s)K- is found in a sample of 85 x 10(6) BB; events, collected with the Belle detector at KEKB, with a branching fraction B(B(0)-->D(+)(s)K-)=(4.6(+1.2)(-1.1)+/-1.3) x 10(-5). We also obtain evidence for the B0-->D(+)(s)pi(-) decay with branching fraction B(B0-->D(+)(s)pi(-))=(2.4(+1.0)(-0.8)+/-0.7) x 10(-5). This value may be used to extract a model-dependent value of |V(ub)|.
Physical Review Letters 12/2002; 89(23):231804. · 7.37 Impact Factor
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R-S Lu,
K Abe,
N Abe,
R Abe,
T Abe,
I Adachi,
H Aihara,
Y Asano,
T Aso,
V Aulchenko, [......],
B D Yabsley,
Y Yamada,
Y Yamashita,
M Yamauchi,
P Yeh,
Y Yuan,
J Zhang,
Z P Zhang,
Y Zheng,
D Zontar
[show abstract]
[hide abstract]
ABSTRACT: We report the first observation of the charmless two-body mode B+/--->omegaK+/- decay, and a new measurement of the branching fraction for the B+/--->omegapi(+/-) decay. The measured branching fractions are B(B+/--->omegaK+/-)=(9.2(+2.6)(-2.3)+/-1.0)x10(-6) and B(B+/--->omegapi(+/-))=(4.2(+2.0)(-1.8)+/-0.5)x10(-6). We also measure the partial rate asymmetry of B+/--->omegaK+/- decays and obtain A(CP)=-0.21+/-0.28+/-0.03. The results are based on a data sample of 29.4 fb(-1) collected on the Upsilon(4S) resonance by the Belle detector at the KEKB e(+)e(-) collider.
Physical Review Letters 11/2002; 89(19):191801. · 7.37 Impact Factor
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K Abe,
T Abe,
I Adachi,
Byoung Sup Ahn,
H Aihara,
M Akatsu,
Y Asano,
T Aso,
V Aulchenko,
T Aushev, [......],
P Yeh,
M Yokoyama,
K Yoshida,
Y Yuan,
Y Yusa,
C C Zhang,
J Zhang,
Y Zheng,
V Zhilich,
D Zontar
[show abstract]
[hide abstract]
ABSTRACT: We present a measurement of CP-violating asymmetries in B0-->pi(+)pi(-) decays based on a 41.8 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. We fully reconstruct one neutral B meson as a B0-->pi(+)pi(-) CP eigenstate and identify the flavor of the accompanying B meson from its decay products. From the asymmetry in the distribution of the time intervals between the two B meson decay points, we obtain the CP-violating asymmetry parameters S(pipi)=-1.21(+0.38)(-0.27)(stat)+0.16-0.13(syst) and A(pipi)=+0.94(+0.25)(-0.31)(stat)+/-0.09(syst).
Physical Review Letters 08/2002; 89(7):071801. · 7.37 Impact Factor
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K Abe,
T Abe,
I Adachi,
H Aihara,
M Akatsu,
Y Asano,
T Aso,
V Aulchenko,
T Aushev,
A M Bakich, [......],
Y Yamashita,
M Yamauchi,
M Yokoyama,
Y Yuan,
Y Yusa,
C C Zhang,
J Zhang,
Y Zheng,
V Zhilich,
D Zontar
[show abstract]
[hide abstract]
ABSTRACT: We report the first observation of chi(c2) production in B meson decays. We find an inclusive B-->chi(c2)X branching fraction of (1.80(+0.23)(-0.28)+/-0.26) x 10(-3). The data set, collected with the Belle detector at the KEKB e(+)e(-) collider, consists of 31.9 x 10(6) BB events. We also present branching fractions and momentum spectra for both chi(c1) and chi(c2) production.
Physical Review Letters 07/2002; 89(1):011803. · 7.37 Impact Factor
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K Abe,
R Abe,
T Abe,
I Adachi,
Byoung Sup Ahn,
H Aihara,
M Akatsu,
Y Asano,
T Aso,
V Aulchenko, [......],
H Yamamoto,
Y Yamashita,
M Yamauchi,
S Yanaka,
P Yeh,
M Yokoyama,
Y Yuan,
J Zhang,
Y Zheng,
D Zontar
[show abstract]
[hide abstract]
ABSTRACT: We report the observation of the decay mode B(+/-) --> p(-)pK(+/-)based on an analysis of 29.4 fb(-1) of data collected by the Belle detector at KEKB. This is the first example of a b-->s transition with baryons in the final state. The p(-)p mass spectrum in this decay is inconsistent with phase space and is peaked at low mass. The branching fraction for this decay is measured to be B(B+/--->p(-)pK+/-) = [4.3(+1.1)(-0.9)(stat)+/-0.5(syst)]x 10(-6). We also report upper limits for the decays B(0)-->p(-)pK(S) and B(+/-)-->p(-)p pi(+/-).
Physical Review Letters 06/2002; 88(18):181803. · 7.37 Impact Factor
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K Abe,
R Abe,
T Abe,
I Adachi,
Byoung Sup Ahn,
H Aihara,
M Akatsu,
Y Asano,
T Aso,
T Aushev, [......],
S Yanaka,
J Yashima,
M Yokoyama,
Y Yuan,
Y Yusa,
C C Zhang,
J Zhang,
Y Zheng,
V Zhilich,
D Zontar
[show abstract]
[hide abstract]
ABSTRACT: The lifetimes of the B(0) and B- mesons are extracted from 29.1 fb(-1) of data collected with the Belle detector at the KEK B factory. A fit to the decay length differences of neutral and charged B meson pairs, measured in events where one of the B mesons is fully reconstructed in several hadronic modes, yields tau(B(0)) = 1.554+/-0.030(stat)+/-0.019(syst) ps, tau(B-) = 1.695+/-0.026(stat)+/-0.015(syst) ps, and tau(B-)/tau(B(0)) = 1.091+/-0.023(stat)+/-0.014(syst).
Physical Review Letters 05/2002; 88(17):171801. · 7.37 Impact Factor
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K. Abe,
R. Abe,
T. Abe,
I. Adachi,
Byoung Sup Ahn,
H. Aihara,
M. Akatsu,
Y. Asano,
T. Aso,
V. Aulchenko, [......],
H. Yamamoto,
Y. Yamashita,
M. Yamauchi,
S. Yanaka,
P. Yeh,
M. Yokoyama,
Y. Yuan,
J. Zhang,
Y. Zheng,
D. Žontar
[show abstract]
[hide abstract]
ABSTRACT: We report the observation of the decay mode
B+/--->ppbarK+/- based on an analysis of 29.4
fb-1 of data collected by the Belle detector at KEKB. This is
the first example of a b-->s transition with baryons in the final
state. The ppbar mass spectrum in this decay is inconsistent with phase
space and is peaked at low mass. The branching fraction for this decay
is measured to be B(B+/--->ppbarK+/-) =
[4.3+1.1-0.9(stat)+/-0.5(syst)]×10-6.
We also report upper limits for the decays
B0-->ppbarKS and
B+/--->ppbarπ+/-.
Physical Review Letters 04/2002; 88(18):181803. · 7.37 Impact Factor
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K Abe,
R Abe,
I Adachi,
B S Ahn,
H Aihara,
M Akatsu,
G Alimonti,
K Asai,
M Asai,
Y Asano, [......],
M Yokoyama,
K Yoshida,
Y Yusa,
H Yuta,
C C Zhang,
J Zhang,
H W Zhao,
Y Zheng,
V Zhilich,
D Zontar
[show abstract]
[hide abstract]
ABSTRACT: We present a measurement of the standard model CP violation parameter sin2 phi(1) based on a 29.1 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. One neutral B meson is fully reconstructed as a J/psi K(S), psi(2S)K(S), chi(c1)K(S), eta(c)K(S), J/psi K(L), or J/psi K(*0) decay and the flavor of the accompanying B meson is identified from its decay products. From the asymmetry in the distribution of the time intervals between the two B meson decay points, we determine sin2 phi(1) = 0.99+/-0.14(stat)+/-0.06(syst). We conclude that we have observed CP violation in the neutral B meson system.
Physical Review Letters 09/2001; 87(9):091802. · 7.37 Impact Factor
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K Abe,
I Adachi,
B S Ahn,
H Aihara,
M Akatsu,
G Alimonti,
K Aoki,
K Asai,
M Asai,
Y Asano, [......],
S Yanaka,
M Yokoyama,
K Yoshida,
Y Yusa,
H Yuta,
C C Zhang,
H W Zhao,
Y Zheng,
V Zhilich,
D Zontar
[show abstract]
[hide abstract]
ABSTRACT: We report a determination of the B(0)(d)-&B_(0)(d) mixing parameter Deltam(d) based on the time evolution of dilepton yields in Upsilon(4S) decays. The measurement is based on a 5.9 fb(-1) data sample collected by the Belle detector at KEKB. The proper-time difference distributions for same-sign and opposite-sign dilepton events are simultaneously fitted to an expression containing Deltam(d) as a free parameter. Using both muons and electrons, we obtain Deltam(d) = 0.463+/-0.008 (stat)+/-0.016 (syst) ps(-1). This is the first determination of Deltam(d) from time evolution measurements at the Upsilon(4S). We also place limits on possible CPT violations.
Physical Review Letters 04/2001; 86(15):3228-32. · 7.37 Impact Factor
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A Abashian,
K Abe,
I Adachi,
B S Ahn,
H Aihara,
M Akatsu,
G Alimonti,
K Aoki,
K Asai,
M Asai, [......],
M Yokoyama,
K Yoshida,
Y Yusa,
H Yuta,
C C Zhang,
H W Zhao,
J Zhang,
Y Zheng,
V Zhilich,
D Zontar
[show abstract]
[hide abstract]
ABSTRACT: We present a measurement of the standard model CP violation parameter sin2 phi(1) (also known as sin2beta) based on a 10.5 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) collider. One neutral B meson is reconstructed in the J/psiK(S), psi(2S)K(S), chi(c1)K(S), eta(c)K(S), J/psiK(L), or J/psipi(0) CP-eigenstate decay channel and the flavor of the accompanying B meson is identified from its charged particle decay products. From the asymmetry in the distribution of the time interval between the two B-meson decay points, we determine sin2 phi(1) = 0.58(+0.32)(-0.34)(stat)+0.09-0.10(syst).
Physical Review Letters 04/2001; 86(12):2509-14. · 7.37 Impact Factor
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Y. Chao,
P Chang,
K Abe,
N Abe,
I. Adachi,
H. Aihara,
K. Akai,
M. Akatsu,
M. Akemoto,
Y Asano, [......],
Y Igarashi,
T Iijima,
H Ikeda,
A. Imoto,
K. Inami,
A Ishikawa,
H. Ishino,
K Itoh,
R. Itoh,
M Iwamoto
[show abstract]
[hide abstract]
ABSTRACT: The evidence for direct charged particles (CP) violation in the decay B0→K+ π- was investigated with 253 fb-1 of data collected with the Belle detector at the KEKB e + e- collider. 275 x 106 BB̄ pairs were used to observe a B→K±π∓ signal with 2140 ±53 events. Mixing induced CP violation in the B sector was established in b → cc̄s transitions. The result suggests large interference between tree and penguin diagrams and the existence of final state interactions.
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K Abe,
N Abe,
T Abe,
I. Adachi,
H. Aihara,
K. Akai,
M. Akatsu,
M. Akemoto,
Y Asano,
T. Aushev, [......],
P. Križan,
P. Krokovny,
T Kubo,
R. Kulasiri,
S Kumar,
A. Kuzmin,
Y.-J. Kwon,
J. S. Lange,
G Leder,
S H Lee
[show abstract]
[hide abstract]
ABSTRACT: We present an improved measurement of CP-violating asymmetries in B 0→π+π- decays based on a 78 fb -1 data sample collected at the Y(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider. We reconstruct one neutral B meson as a B0→π+π - CP eigenstate and identify the flavor of the accompanying B meson from inclusive properties of its decay products. We apply an unbinned maximum likelihood fit to the distribution of the time intervals between the two B meson decay points. The fit yields the CP-violating asymmetry amplitudes A ππ= +0.77 ±0.27(stat) ±0.08(syst) and S ππ=-1.23 ±0.41(stat) -0.07 +0.08(syst), where the statistical uncertainties are determined from the Monte Carlo pseudoexperiments. We obtain confidence intervals for CP-violating asymmetry parameters Aππ and Sππ based on a frequentist approach. We rule out the CP-conserving case, A ππ=Sππ=0, at the 99.93% confidence level. We discuss how these results constrain the value of the Cabibbo-Kobayashi-Maskawa (CKM) angle φ2. © 2003 The American Physical Society.
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N. C. Hastings,
K Abe,
R Abe,
T Abe,
I. Adachi,
H. Aihara,
M. Akatsu,
Y Asano,
T Aso,
V. Aulchenko, [......],
S Kumar,
A. Kuzmin,
Y.-J. Kwon,
J. S. Lange,
G Leder,
S H Lee,
J Li,
S.-W. Lin,
D. Liventsev,
R. S. Lu
[show abstract]
[hide abstract]
ABSTRACT: We report a precise determination of the Z0-B̄0 mixing parameter Δmd based on the time evolution of same-sign and opposite-sign dilepton yields in Y(45) decays. Data were collected with the Belle detector at KEKB. Using data samples of 29.4 fb-1 recorded at the γ(4S) resonance and 3.0 fb-1 recorded at an energy 60 MeV below the resonance, we measure Δmd=[0.503±0.008(stat) ±0.010(syst)] ps-1. From the same analysis, we also measure the ratio of charged and neutral B meson production at the γ(4S), f +/f0= 1-01 ±0.03(stat)±0.09(syst), and CPT violation parameters in B0-B̄0 mixing, (cos θ)=0.00±0.12(stat) ±0.01(syst) and ℑ(cos θ)=0.03±0.01(stat)±0.03(syst). © 2003 The American Physical Society.
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R. Abe,
T. Abe,
H. Aihara,
Y. Asano,
T. Aso,
A. Bakich,
T. Browder,
M.C. Chang,
Y. Chao,
K.F. Chen, [......],
Y. Yamada,
H. Yamamoto,
Y. Yamashita,
M. Yamauchi,
H. Yanai,
R. Yang,
Y. Yasu,
M. Yokoyama,
T. Ziegler,
D. Zontar
[show abstract]
[hide abstract]
ABSTRACT: We have upgraded the beampipe and the silicon vertex tracker of the Belle detector for increased luminosity and to achieve better vertex resolution. The radius of the beampipe was reduced from 2 to 1.5 cm to achieve better vertex resolution. In order to reduce the beam background that could accompany the reduction of the beampipe radius, a massive mask made of tantalum and tungsten was placed on each side of the central section. The total weight of them is 40 kg. The maximum radiation dose of the silicon tracker is measured about 80 krad/yr. This is lower than the dose of 100 krad per year with the previous beampipe even though the beampipe radius is smaller. The beampipe is designed to minimize heating, and enough cooling power is provided by the liquid cooling.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment.
