Storage Ring Adone Research Articles

Bruno Touschek: From Betatrons to Electron–Positron Colliders

Bruno Touschek’s life as a physicist spanned the period from World War II to the 1970s. He was a key figure in the developments of electron–positron colliders and storage rings, and made important contributions to theoretical high energy physics. Storage rings, initially developed for high energy physics, are being widely used in many countries as synchrotron radiation sources and are a tool for research in physics, chemistry, biology, environmental sciences and cultural heritage studies. We describe Touschek’s life in Austria, where he was born, in Germany, where he participated in the construction of a betatron during WWII, and in Italy, where he proposed and led to completion the first electron–positron storage ring in 1960, in Frascati. We highlight how his central European culture influenced his lifestyle and work, and his main contributions to physics, such as the discovery of the Touschek effect and beam instabilities in the larger storage ring ADONE.

Deuteron photo-disintegration with polarised photons in the energy range 30–50 MeV

The reaction d( γ, np) has been studied using the tagged and polarised LADON gamma ray beam at an energy 30–50 MeV to investigate the existence of narrow dibaryonic resonances recently suggested from the experimental measurements in a different laboratory. The beam was obtained by Compton back-scattering of laser light on the electrons of the storage ring ADONE. Photo-neutron yields were measured at five neutron angle υ n c.m. = 22°, 55.5°, 90°, 125° and 157° in the center of mass system. Our results do not support the existence of such resonances.

The influence of transition metals on the electronic structure of ZnSe host crystal: fundamental reflectivity analysis

The optical properties of the semiconducting compounds (Me = Ti, V, Cr, Mn, Fe, Co, and Ni) crystallizing in the zinc-blende structure have been investigated. Reflectivity spectra of these materials have been taken at room and liquid nitrogen temperatures. The measurements have been performed in the 4 - 25 eV energy range using synchrotron radiation from the ADONE storage ring in Frascati. Comparisons between the reflectivity spectra of the ternary systems and those of the host crystal ZnSe have been made, and models explaining the influence of the transition metal ions on the electronic structure of the host crystal ZnSe have been discussed.

Measurement of the total e +e − → hadrons cross section near the e +e − →N [formula omitted] threshold

A new measurement of the total e +e − → hadrons cross-section in the centre of mass energy range 1.8-2.5 GeV, performed by the FENICE experiment at the Frascati e +e − storage ring ADONE, is presented. The behaviour of the total cross section together with the proton electromagnetic time-like form factor is discussed in terms of a narrow vector resonance close to the nucleon-antinucleon threshold.

First measurement of the neutron electromagnetic form factors in the timelike region

The first measurement of the neutron form factors in the timelike region has been produced by studying the e+e-⟹ $$\bar nn$$ reaction at variousE c. m. at the ADONE storage ring. Results at 2.0 GeV and 2.1 GeV, based on the analysis of one third of the data on tape, are reported here.

Measurement of the electromagnetic form factor of the proton in the time-like region

The cross section for the process e +e − → p p has been measured in the s range 3.6–5.9 GeV 2 by the FENICE experiment at the e + e − Adone storage ring and the proton electromagnetic form factor has been extracted.

Gas bremsstrahlung: a comparison of measurements and simulations

The absolute bremsstrahlung intensity generated by the interaction of the electron beam of the Adone storage ring of LNF has been measured as a function of angle and distance from the emitting straight section. Absorbed doses have been measured at various distances from the straight section by means of thermoluminescent dosimeters for a 1.5 GeV electron beam. The experiment has been simulated using the most recent version of the FLUKA code which includes a very accurate treatment of bremsstrahlung. In spite of the considerable uncertainties on the experimental value of the pressure, it has been found that the computed results are in satisfactory agreement with the results of the measurements. The experiment provided also evidence for the angular distribution of the bremsstrahlung intensity at energies in excess of 1 GeV.

The FENICE detector at the e+e− collider ADONE

Abstract The FENICE detector, installed at the Frascati e+ e− storage ring ADONE, for measuring the neutron e.m. form factors in the timelike region, is described. FENICE is a nonmagnetic detector and consists of a complex array of scintillators, limited streamer tubes and iron converters for detecting mainly the process e + e − → n n . Antineutrons are identified by the charged prongs produced in their annihilation and the antineutron velocity is measured by the retrieved annihilation time with respect to the beam crossing time. Neutrons are detected in plastic scintillator layers. To reduce the cosmic rays background a concrete shield, covered by an active veto system, is added.

A new measurement of [formula omitted

A new measurement of the branching ratio of J ψ→n n , B n n =(1.90±0.55)×10 −3 , has been achieved by the FENICE detector at the e + e − storage ring ADONE in Frascati.

The Frascati tagged photon beam from a molecular beam radiator

We describe the new monochromatic photon beam obtained at Frascati by tagging the bremsstrahlung, on a molecular beam radiator, of the electrons circulating in the Adone storage ring. The tagging system installed in one ring dipole, consists of two scintillation counter arrays defining 76 channels of 0.9% resolution (FWHM) at 1500 MeV. The system can tag photons at rates up to 5×10 7 s −1 in the range 200–1200 MeV.

Taladon: a polarized and tagged gamma ray beam

We present the first measurements of the gamma-ray beam energy resolution obtained with a new tagging system for the Ladon facility on the storage ring Adone at Frascati. A resolution of the order of 3% in the energy region of 30–80 MeV is obtained in accordance with predictions.

Superconducting wiggler for adone: Design and present status

A superconducting wiggler has been designed and built at Laboratori Nazionali INFN in Frascati, Italy, in collaboration with Ansaldo Componenti-Genova, to be used as an insertion device in the Adone storage ring. It will be used as a light source on the 1.5 GeV, 100 mA electron beam of the accelerator, to produce about 1012 photons/s/mrad in 0.1% band width, in the short X-ray wavelength range. In order to minimize the electron beam orbit disortion and to obtain the best phase space distribution of the generated synchrotron radiation (a single bright spot), a superconducting dipole, producing a sharp vertical field peak (6 T, 12 cm FWHM), between two normal conducting side dipoles (0.8T), to compensate the field integral, has been manufactured. The s.c. dipole is made up of 2NbTi coils, separated by a central plate and kept together by two 356 kg total weight iron yokes. The magnet gap is 6 cm and the design current is 360A. The system is contained in a warm bore cryostat and cooled by boiling helium at 4.6K. The static cryostat helium consumption is of 41/h and, when the cryomagnet is energized, it is cooled by a 1430S Koch liquefier/refrigerator on line with it through transfer lines. The stored energy is 184 kJ. This paper describes the latest status of the facility and the verification tests.

The quench analysis of a 6 T SC wiggler for Adone at Frascati

A single-pole, 6-T, superconducting wiggler with two racetrack NbTi superconducting coils separated by a central plate and kept together by two iron yokes has been designed and built. The superconducting magnet and two low-field compensating warm poles will be installed in the straight section no.10 of the e/sup +/,e/sup -/ storage ring Adone, to be used as a wavelength shifter to produce a hard X-ray flux of 2.4*10/sup 12/ photons/s/mrad in 0.1% bandwidth at a critical energy of 9 keV, six times higher than the one produced by the accelerator bending magnets. An analysis is presented of a typical quench.

The argon cluster beam installed in the ADONE storage ring

The argon cluster beam, with a maximum thickness of 1.5 × 10 14 atoms/cm 2, installed at Frascation the ADONE storage ring, is described. The cluster beam works at room temperature and is used as radiator to produce an intense tagged photon beam with energy up to 1.2 GeV. The argon bea, properties were measured using electrons stored in ADONE; the results are in good agreement with the expected values. The apparatus can produce cluster beams of higher thickness and work with different gases. It is suitable for internal target experiments with the 1.5 GeV stored electrons.

Internal target effects in the ADONE storage ring

The effect of a thin (10 −10−10 −8 g cm −2) argon jet target on the beam quality in the ADONE storage ring was studied. The beam emittance growth and electron loss, due to Coulomb scattering, were discussed in the light of the damping mechanism: no effect was expected and observed for electron energies ≥ 500 MeV. The beam lifetime was calculated and measured for different target thicknesses, and was shown to be essentially due to bremsstrahlung processes on the jet target.

Ray tracing results for a doubly focusing independent crystal X-ray monochromator

The need to monochromatize and focus X-rays emitted into appreciable horizontal apertures by storage ring sources (bending magnets and wigglers) leads to the design of focusing monochromators. In order to optimize their design, it is important to understand the combined effect of focusing and diffraction of the flux available at the sample. We analyze here the combined effect of focusing and diffraction for a double-crystal monochromator which is being designed for the Superconducting Wiggler beamline (SCOW) on the ADONE storage ring in Frascati. A double-separated crystal system has been chosen; we study the possibility of obtaining focalization in two steps, by dynamically bending the crystals in order to obtain both tangential and sagittal focusing. Non-focusing and semi-focusing systems have also been considered. The calculations have been performed with the ray tracing program SHADOW. We estimate performances for various focusing geometries and consider the effect of anticlastic curvature.

The Adone wiggler x-ray lithography beamline

A soft x-ray beamline, utilizing the radiation produced by the six-pole wiggler of the Adone storage ring, has been realized. The beamline allows the exposure of large area resists by means of a double-mirror scanning system or mechanically moving the wafer. The mechanical, geometrical, and spectral characteristics of the beamline will be described.

Extension of two-photon spectroscopy to the vacuum ultraviolet using synchrotron radiation

The experimental apparatus, built at the ADONE storage ring in Frascati, and using a Q-switched Nd:YAG laser as a powerful source is presented. Space and time superposition of the beams is discussed extensively. Testing of the apparatus has been performed by measuring the two-photon absorption spectra of KCl and NaCl.

Polarization asymmetry in the photodisintegration of the deuteron.

The reaction $^{2}(\ensuremath{\gamma}$,p)n has been studied using a monochromatic and polarized gamma ray beam at energies ${E}_{\ensuremath{\gamma}}$=19.8, 29.0, 38.6, and 60.8 MeV. The beam of an intensity \ensuremath{\sim}4\ifmmode\times\else\texttimes\fi{}${10}^{5}$ \ensuremath{\gamma}/sec was obtained by Compton back scattering of mode-locked laser light off electron bunches in the Adone storage ring. Photoneutron yields were measured at nine neutron angles ${\mathrm{theta}}_{\mathrm{n}\mathrm{\ensuremath{\simeq}}}$15, 30, 45, 60, 90, 120, 135, 150, and 165 deg in the center of mass (c.m.) for ${E}_{\ensuremath{\gamma}}$=19.8, 29.0, and 38.6 MeV, and at ${\mathrm{theta}}_{\mathrm{n}\mathrm{\ensuremath{\simeq}}}$30, 60, 90, 120, and 150 deg c.m. for ${E}_{\ensuremath{\gamma}}$=60.8 MeV. The polarization independent component ${I}_{0}$(theta) of the differential cross section and the polarization dependent component ${\mathrm{PI}}_{1}$(theta) were deduced and the angular distribution of the azimuthal asymmetry factor \ensuremath{\Sigma}(theta)=${I}_{1}$(theta)/${I}_{0}$(theta) was obtained. An extensive comparison with theory has been carried out and the inclusion of corrections due to meson exchange currents and to \ensuremath{\Delta}-isobar configurations have been shown to be mandatory at energies ${E}_{\ensuremath{\gamma}}$\ensuremath{\gtrsim}40 MeV. Theoretical and experimental implications of intermediate energy deuteron photo- disintegration studies are discussed in some detail.

Reduction of Multipacting in an Accelerator Cavity

The choice of a suitable geometry in designing a radio-frequency cavity for e+ e- storage ring allows the reduction of multipacting (MP) discharges. We have studied the behaviour of resonant electron discharges in the RF cavity of the Adone storage ring in Frascati, that shows a broad MP barrier in the 35 to 70 kV range of the accelerating voltage. It can be explained by one point MP on the end-plates of the resonator. Our computer simulations of the trajectories of electrons in the RF fields of the cavity clearly show multipacting trajectories in that region of the cavity at about that field level. On the base of our experimental measurements and simulations, the design of a new RF cavity, multipactor free in the end-plates region, is presented.