SuperKEKB
is a
particle collider
A collider is a type of particle accelerator which brings two opposing particle beams together such that the particles collide. Colliders may either be ring accelerators or linear accelerators.
Colliders are used as a research tool in particle ...
located at
KEK
, known as KEK, is a Japanese organization whose purpose is to operate the largest particle physics laboratory in Japan, situated in Tsukuba, Ibaraki prefecture. It was established in 1997. The term "KEK" is also used to refer to the laboratory ...
(''High Energy Accelerator Research Organisation'') in
Tsukuba
is a city located in Ibaraki Prefecture, Japan. , the city had an estimated population of 244,528 in 108,669 households and a population density of 862 persons per km². The percentage of the population aged over 65 was 20.3%. The total ar ...
,
Ibaraki Prefecture
is a Prefectures of Japan, prefecture of Japan located in the Kantō region of Honshu. Ibaraki Prefecture has a population of 2,871,199 (1 June 2019) and has a geographic area of . Ibaraki Prefecture borders Fukushima Prefecture to the north, ...
,
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
. SuperKEKB collides
electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no kn ...
s with
positron
The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. It has an electric charge of +1 '' e'', a spin of 1/2 (the same as the electron), and the same mass as an electron. When a positron collides ...
s at the centre-of-momentum energy close to the mass of the
Υ(4S) resonance
Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscillatin ...
making it a second-generation
B-factory In particle physics, a B-factory, or sometimes a beauty factory, is a particle collider experiment designed to produce and detect a large number of B mesons so that their properties and behavior can be measured with small statistical uncertainty. T ...
for the
Belle II experiment. The accelerator is an upgrade to the
KEKB KEKB may refer to:
* KEKB (accelerator)
* KEKB (FM)
KEKB is a radio station serving Grand Junction, Colorado and its vicinity with a country music format. This station broadcasts on FM frequency 99.9 MHz and is under ownership of Townsquare ...
accelerator, providing approximately 40 times higher
luminosity
Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a st ...
,
due mostly to
superconducting
Superconductivity is a set of physical properties observed in certain materials where Electrical resistance and conductance, electrical resistance vanishes and magnetic field, magnetic flux fields are expelled from the material. Any material e ...
quadrupole focusing magnets.
The accelerator achieved "first turns" (first circulation of electron and positron beams) in February 2016. First collisions occurred on 26 April 2018. At 20:34 on 15 June 2020, SuperKEKB achieved the world’s highest instantaneous luminosity for a colliding-beam accelerator, setting a record of 2.22×10
34 cm
−2s
−1.
Description
The SuperKEKB design reuses many components from KEKB.
Under normal operation, SuperKEKB collides
electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no kn ...
s at 7 GeV with
positron
The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. It has an electric charge of +1 '' e'', a spin of 1/2 (the same as the electron), and the same mass as an electron. When a positron collides ...
s at 4 GeV
(compared to KEKB at 8 GeV and 3.5 GeV respectively). The centre-of-momentum energy of the collisions is therefore at the mass of the
Υ(4S) resonance (10.58 GeV/c
2). The accelerator will also perform short runs at energies of other
Υ resonance
Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscillatin ...
s, in order to obtain samples of other B mesons and baryons.
The asymmetry in the beam energy provides a relativistic
Lorentz boost
In physics, the Lorentz transformations are a six-parameter family of linear transformations from a coordinate frame in spacetime to another frame that moves at a constant velocity relative to the former. The respective inverse transformation i ...
to the
B meson
In particle physics, B mesons are mesons composed of a bottom antiquark and either an up (), down (), strange () or charm quark (). The combination of a bottom antiquark and a top quark is not thought to be possible because of the top quark' ...
particles produced in the collision. The direction of the higher-energy beam determines the 'forward' direction, and the affects the design of much of the
Belle II detector
The BelleII experiment is a particle physics experiment designed to study the properties of B mesons (heavy particles containing a beauty quark) and other particles. BelleII is the successor to the Belle experiment, and commissioned at the Supe ...
.
As with
KEKB KEKB may refer to:
* KEKB (accelerator)
* KEKB (FM)
KEKB is a radio station serving Grand Junction, Colorado and its vicinity with a country music format. This station broadcasts on FM frequency 99.9 MHz and is under ownership of Townsquare ...
, SuperKEKB consists of two storage rings: one for the high-energy electron beam (the High Energy Ring, HER) and one for the lower energy positron beam (the Low Energy Ring, LER). The accelerator has a circumference of 3016m with four straight sections and experimental halls in the centre of each, named "Tsukuba", "Oho", "Fuji", and "Nikko".
The
Belle II experiment is located at the single interaction point in Tsukuba Hall.
Luminosity
The target
luminosity
Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a st ...
for SuperKEKB is 6.5×10
35 cm
−2s
−1, this is 30 times larger than the luminosity at
KEKB KEKB may refer to:
* KEKB (accelerator)
* KEKB (FM)
KEKB is a radio station serving Grand Junction, Colorado and its vicinity with a country music format. This station broadcasts on FM frequency 99.9 MHz and is under ownership of Townsquare ...
. The improvement is mostly due to a so-called 'nano-beam' scheme, originally proposed for the cancelled
SuperB
Superb may refer to:
*Škoda Superb car
*, nine Royal Navy ships
*The Superb
The ''Superb'' was used as U.S. President Warren G. Harding's personal Pullman railroad car in a cross-country tour in 1923. After Harding's death, the car returned hi ...
experiment. In the nano-beam scheme at SuperKEKB, the beams are squeezed in the vertical direction and the crossing angle is increased, which reduces the area of the crossing.
The luminosity is further increased by a factor of two, due to a higher beam current than KEKB.
The focus and crossing angle is achieved by two new
superconducting
Superconductivity is a set of physical properties observed in certain materials where Electrical resistance and conductance, electrical resistance vanishes and magnetic field, magnetic flux fields are expelled from the material. Any material e ...
quadrupole magnets at the interaction point
that were installed in February 2017.
On June 15, 2020, SuperKEKB set a new world record for the highest instantaneous luminosity for a colliding-beam accelerator: 2.22×10
34 cm
−2s
−1. (On June 21, 2020, SuperKEKB broke its own record and achieved an instantaneous luminosity of 2.40×10
34 cm
−2s
−1.) The previous world record of 2.14×10
34 cm
−2s
−1 was achieved by
LHC
The Large Hadron Collider (LHC) is the world's largest and highest-energy particle collider. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008 in collaboration with over 10,000 scientists and hundre ...
in 2018.
[{{Cite web, title=SuperKEKB collider achieves the world's highest luminosity, url=https://www.interactions.org/press-release/superkekb-collider-achieves-worlds-highest-luminosity, access-date=2020-09-08, website=Interactions, language=en]
See also
*
KEKB KEKB may refer to:
* KEKB (accelerator)
* KEKB (FM)
KEKB is a radio station serving Grand Junction, Colorado and its vicinity with a country music format. This station broadcasts on FM frequency 99.9 MHz and is under ownership of Townsquare ...
*
Large Electron-Positron Collider
*
Large Hadron Collider
The Large Hadron Collider (LHC) is the world's largest and highest-energy particle collider. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008 in collaboration with over 10,000 scientists and hundred ...
References
External links
SuperKEKB webpageKEK webpageSuperKEKB on
INSPIRE-HEP INSPIRE-HEP is an open access digital library for the field of high energy physics (HEP). It is the successor of the Stanford Physics Information Retrieval System (SPIRES) database, the main literature database for high energy physics since the 1970 ...
Belle II on
INSPIRE-HEP INSPIRE-HEP is an open access digital library for the field of high energy physics (HEP). It is the successor of the Stanford Physics Information Retrieval System (SPIRES) database, the main literature database for high energy physics since the 1970 ...
Particle physics facilities
Particle experiments
B physics
Accelerator physics
Particle accelerators
Science and technology in Japan
Tsukuba, Ibaraki