The particle and nuclear physics research is carried out at the Electron-Positron collider DAFNE.
The DAFNE complex is composed by a LINAC feeding an accumulator/damping ring that injects positrons and electrons into two identical but separate storage rings.
The collider is optimized to work at the F mass with a target luminosity L= 5 x 1032 cm-2 s-1.
The strategy used to reach the target luminosity
is to obtain the same single bunch luminosity achieved at VEPP-2M and to
increase the number of bunches (up to 120).
The electrons and the positrons circulate in two separate
rings and collide at two interaction points with an horizontal crossing
angle of 12.5 mrad to minimize the effect of parasitic collisions.
The multibunch instability is fought by a digital feedback system.
Taking advantage of its luminosity, several high-precision experiments will be carried out with 3 detectors: the K-Long Observation Experiment (KLOE) for the measurement of CP violation in kaon decays in one of the two interaction region , a nuclear physics detector (FINUDA) and a detector for researching in the field of exotic atoms (DEAR) in the other.
The machine commissioning was successfully completed during
1998 with a provisional interaction region without solenoidal field. In
March 1999 the first test run with the
KLOE
magnetic detector began. The machine has been operated in the single and
multibunch mode reaching a luminosity of ~ 4 x 1030
cm-2 s-1.
Synchrotron Radiation Laboratory DAFNE-Light for applied physics and multidisciplinary and biomedical physics (1999)
The new collider, DAFNE, is also a source of synchrotron radiation, from the infrared to the soft x-rays range. The synchrotron light laboratory (DAPHNE-Light) will offer many opportunities to experimental programs in this extended energy range using a wiggler and a bending magnet source.
The synchrotron light laboratory will offer access to experimental apparata installed on two separate beamlines.
The first one is a beamline that collects the radiation
emitted by one multipole wiggler having a critical energy of 310 eV. The
beamline equipped with a double crystal fixed exit monochromator will be
used for spectroscopy and diffraction experiments in the x-ray range between
1 and 7 keV.
The end station of the wiggler beamline hosts an experimental
area dedicated to large exposition and LIthoGAlvanoformic (LIGA) process
where a x-ray stepper KARL SUSS is located in a "clean room" of class A100.
to be used in technological and biomedical applications.
The laboratory is equipped to realise all lithographic
processes, including a SEM of ABT 130S type with an ELPHY III tool that
allow Electron Beam lithography processes. The system with a proper SW
and HW allows the realisation of nanostructures of microdevices. All the
equipment may be used to realise sensors or microdevices for technological
and biomedical applications. or may be used in the technology of the RX
masks production
We expect users interested to utilise the wiggler beamline
for spectroscopy and diffraction experiments, but also project research
teams interested to the development of LIGA processes.
The unique characteristics of the DAFNE
ring, i.e., high current (I>5 A) and low energy (0.51 GeV) make it very
powerful for applications in the IR range. As a consequence, the second
beamline, SINBAD, is an infrared port from a bending magnet, and the expected
brilliance gain of this SR source, compared to an intense thermal source,
like a black body at 2000 K is about two order of magnitude in the far
IR.
The optical system of the beamline, that allow to conserve
the high intensity, is designed to match several dedicated equipments:
a Bruker Equinox interferometer modified for vacuum operation, covering the range 10-12000 cm-1 with a resolution of 0.5 cm-1, equipped for both transmittance and reflectance measurements;These apparata make this beamline, suitable for experiments in multidisciplinary areas, i.e., in biophysics, solid state physics and material science, almost unique in Europe if not in the world.a Bruker microscope working in the range 400-6000 cm-1, equipped with computer-controlled sample stage;
a closed-cycle and liquid helium cryostats;
a grating monochromator able to operate between the nIR and 12 mm.
Particle and Nuclear physics facilities (1998)
The particle and nuclear physics researches are a front-line
research program at the LNF. The particle and nuclear physics research
is carried out at the electron-positron collider
DAFNE.
It consists of a double colliding ring for electrons
and positrons with 510 MeV energy per beam. More in detail, there is a
LINAC feeding an accumulator that injects positrons and electrons into
two identical but separate storage rings. They cross at half angle between
10 and 15 mrad in two interaction regions. This multibunch accelerator,
with a design luminosity of 5x1032 cm-2s-1,
is in an operational phase with 30 bunches, each having a designed luminosity
of about 4x1030 cm-2 sec-1. In the year
2000, the number of bunches is expected to be increased by a factor 4.
Taking advantage of the DAFNE
properties many high-precision experiments can be carried out with the
3 detectors operating at DAFNE,
i.e., KLOE detector for particle
physics, the nuclear physics detector (FINUDA)
and the detector for investigation of low energy kaon nucleon interaction
as well as of SU3 kiral symmetry breaking (DEAR).
These experiments are fully open to collaborations with
EU researchers involved in the related fields. Moreover, new researchers
and/or new proposals are also welcome.
In one of the two interaction region the
KLOE
detector is already operational from 1999. The second interaction region
is devoted to two experiments: DEAR,
that has collected the first data in 1999 and FINUDA
that will complete the detector assembling in the year 2000.
The KLOE
detector has been designed primarily for the measurement of all the relevant
CP and CPT violation parameter in neutral kaon decays. The large amount
of kaon pairs (~ 7 x 109 KS KL) produced in one year at full luminosity
will allow the measurement of Re (e'/e)
with a statistical precision (~ 10-4) comparable to the fixed target experiments
and completely different systematic effects. Moreover the kaon pairs are
produced in an initial state with well defined quantum number (the one
of the photon) and they are almost back to back. These unique feature of
DAFNE
allow the efficient determination of the nature of a kaon by looking
at the decay of the companion in the opposite direction (tagging), and
to perform quantum interferometry measurements.
Using the clean KS beam, obtained by tagging technique,
the measurement of the KS semileptonic asymmetry can be performed for the
first time.
Thanks to the high statistic also the neutral and charge
kaon form factor will be measured with high precision.
Moreover h, h', fo and ao mesons are copiously produced
in F radiative decays. This will allow coverage of a rich wealth of physics
topics beside CP and CPT studies.
DAFNE is also the most intense source in the world of low momentum, high resolution and high purity kaons allowing interesting research programs, such as hypernuclei research with FINUDA and DEAR.
DEAR
(DAFNE
Exotic Atoms Research) is an experiment devoted to a precision measurement
of the scattering lengths of the kaon-nucleon system in kaonic hydrogen
and kaonic deuterium.
In addition to the precise determination of low-energy
parameters, a fundamental non-perturbative QCD quantity, such as the KN
sigma term, undetermined up to now, will be measured. From this quantity
one can derive an indication of the chiral symmetry breaking part
in the total strong interaction Hamiltonian for a nucleon state and a direct
measurement of the strangeness content of the proton.
Main topic of interest of the FINUDA
experiment is the study of Lambda-hypernuclei levels and lifetimes, and
their non-mesonic decays.
Lambda-hypernuclei are produced by stopping negative
kaons from F decays in a thin target, with the prompt negative pion whose
momentum is uniquely related to the energy level of the hypernucleus. By
comparing non-mesonic decays of the hypernucleus into nn and np final states
it is possible to confirm the validity of
DI=1/2
rule in weak interactions.
The Division has been in charge of the construction of DAFNE complex, i.e. the two rings, an accumulator and the LINAC, and presently operates them.
The Division possess a broad and deeply specialised know-how of R&D for new accelerators technology which is world-wide recognised. The development and construction of such advanced facilities required specific competencies, not only in the field of beam dynamics, but also in infrastructures and technologies that are currently available on the premises. These include: a vacuum technology service for developing high-technology solutions, such as those allowing to reach the extreme vacuum conditions in the DAFNE storage rings; machine optics; electronics e.g. multibunch feedback system.
Infrastructures and technologies of the division are currently available. Moreover, an electron (positron) LINAC is available, together with a smaller beam accumulation ring. A new test beam facility is expected to be also available from the new LINAC injector (commissioning during the 2000).
The scientist working in the division are open to collaborations
with other researchers involved in this area. New researchers and/or cooperations
on the on going activities are welcome.
Beam test facility (operational 2000)
The DAFNE beam test facility (BTF) is a beam transfer line designed in order to operate in single electron (or positron) mode stochastically produced.
The BTF will use parasitically the Linac beam of the DAFNE complex with a maximum particle energy of 800 MeV and an energy spread of about 1%.
The main purposes of this facility are test and calibration of detectors.
The beam test facility area is going to be completed before
the end of 2000, experiments could be planned early next year.
Ultracryogenic gravitational-wave observatory NAUTILUS (1995)
Nautilus is a ultracryogenic detector for gravitational
waves. The resonant bar weighing 2.3 tons is operating since 1995 with
liquid helium at the ultra-low temperature of 0.1 K.
At present NAUTILUS
is one of the two most sensitive gravitational wave detector in the world
with a sensitivity of 5x10-22/(Hz)-1/2
at resonance, sufficient to detect impulsive sources located in our galaxy
and in the local group. It can detect gravitational wave burst with amplitude
of 4x10-19 and monochromatic waves with
amplitude of 10-25.
Several different facilities for R&D activities are available:
Researchers interested in the activity of the detector
or in using the available facilities for R&D associated to the antenna
or in data analysis are welcome and will be integrated in the existing
project.
A temperature variable cryostat with an 8T superconducting magnet (1998)
At the LNF a temperature variable cryostat (4-300K) is available, with an 8T superconducting magnet for a.c. magnetic multiharmonic susceptibility and transport measurements, as well as for the determination of the critical current and normal losses in materials like High Temperature Superconductors.
The device allows the record of a.c. magnetic multiharmonic susceptibility up to the first seven harmonic components of the magnetic susceptibility, at low and high dc magnetic field, and transport measurements. The characteristic and the flexibility of this device makes it very rare, if not unique in Europe.
All transport measurements are possible on this device, since 1998 as the higher harmonic susceptometer at low magnetic field. Test using high magnetic fields inside the cryostat are in progress and the commissioning should be completed during the 2000.
This low temperature facilities associated to an intense
magnetic field (8T superconducting magnet) is particularly suitable to
investigate the increase of the superconducting properties loading H in
HTSC samples. The numerical analysis of these experimental data is based
on the magnetic diffusion in HTSC samples for separate isteretic and normal
losses. These studies are possible because the device may change frequency
and amplitude of the a.c. magnetic field probe continuously.
The research group for the biodosimetric porpoises utilises a laboratory of radiation cell biology, which is operated in collaboration with ENEA.
Biological dosimetry is a diagnostic methodology to measure
the individual absorbed dose in the case of accidental overexposure to
ionizing radiation. Biodosimetry could be used also in the following areas:
Research on new biological dosimetry methods to evaluate the dose as a consequence of a radiological incident, as well as the individual susceptibility to ionising radiation, are possible at LNF using a X-ray irradiator and the main radiobiological instrumentation of the medical dosimetry (DOSIME) research group. Moreover, radiobiology experiments and the study of radiation damage induced by accelerated particles in cultured cells are carried out at the LNF Radiation Safety Service laboratory.
The DOSIME research group makes use of a X-ray irradiator
in a laboratory equipped with: laminar flow hood, CO2 incubator, steriliser,
cell freezing, optical microscope, centrifuges, spectrophotometer, X-rays
plant, etc. In addition, radiobiology experiments and the study of radiation
damage induced by accelerated particles in cultured cells are carried out
in this laboratory.
Servizio
di Direzione e M.C.D'Amato
March 29, 2000