Commissioning of the SPARC Movable Emittance Meter and Its First Operation at PITZ

For the SPARC Project a novel diagnostic device, called "Emittance-meter", has been conceived and constructed to perform a detailed study of the emittance compensation process in the SPARC photo-injector and to optimize the RF-gun and the accelerator working point. It consists of a movable emittance measurement system, based on the 1D pepper-pot method, installed between two long bellows with the possibility to scan a region 1.2 m long downstream the RF-gun. The construction of the device was completed in the first part of this year and a series of laboratory tests, to evaluate its performances, were carried out in Spring 2005. At the beginning of the summer the complete system was moved to DESY at Zeuthen to be installed on the Photo Injector Test Facility PITZ. After the commissioning it will used for measurements of the PITZ electron beam in the framework of a collaboration between the SPARC and PITZ Projects aiming on studies and operations with photo injectors

COMMISSIONING OF THE SPARC MOVABLE EMITTANCE METER AND ITS FIRST OPERATION AT PITZ

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Highly Sensitive Beam Size Monitor for pA Currents at the MLS Electron Storage Ring

For the operation of the Metrology Light Source MLS [1], the electron storage ring of the Physikalisch Technische Bundesanstalt PTB , as a primary radiation source standard all storage ring parameters have to be known absolutely. For the measurement of the electron beam size and the control of the stability of the orbit location a new imaging system has been set up, that operates at very different intensity levels covering more than 11 decades, given by the variation of the electron beam current. The system uses a commercial zoom lens for the achromatic optical imaging of the electron beam source point onto two different camera systems. One camera system is for life imaging of the source point at electron beam currents from 200 mA down to some amp; 956;A. The second system is a cooled CCD camera that allows imaging of the electron beam source size and location at very low currents, down to only one stored electro

Beam Transport Lines at BESSY-II

The injection system for the BESSY-II storage ring consists of a 50 MeV microtron and a synchrotron booster which ramps the electron beam to the final operation energy of max. 1.9 GeV. The requirements to be met by the transfer lines from the microtron to the booster and from the booster to the storage ring are discussed and the respective magnetic structures are presented. A "genetic" fitting algorithm to optimize the quadrupole settings in the transfer lines is briefly discussed. I. Introduction The electron beam from a 100 keV diode gun is preaccelerated up to 50 MeV by a conventional racetrack microtron and is injected on-axis into the booster synchrotron using a "fast" kicker in combination with a horizontal septum magnet (393 mrad). At full energy (E max =1.9 GeV) three bumper magnets push the closed orbit close to the extraction septum (196 mrad) and a "fast" kicker (1.8 mrad) extract the beam. Injection into the storage ring is done using two septa with a total deflecting ang..

MESURES DE POLARISATION DE RAIES DU SPECTRE D'ATOMES DE CUIVRE EXCITÉS ET ORIENTÉS PAR IMPACT D'ÉLECTRONS, EN RELATION AVEC L'ÉNERGIE DES ÉLECTRONS ET LA PRÉSENCE D'UN CHAMP MAGNÉTIQUE

Les atomes de cuivre d'un faisceau atomique, pris dans l'état fondamental 4 s 2S1/2- ont été excités par des électrons de quantité de mouvement initiale parallèle à un champ magnétique statique. On a mesuré, pour différentes énergies ( < 200 eV) et dans la direction perpendiculaire au faisceau d'électrons, la polarisation des raies provenant des niveaux 4 p 2P1/2,3/2- et 4 d 2D3/2, 5/2-, en relation avec le champ magnétique statique (entre 0 et 80 œ). Pour la raie 3 273 Å (2P1/2-2S1/2), en accord avec la théorie, on n'a observé aucune polarisation. En ce qui concerne la raie 3 247 Å (2P3/2-2S1/2), le champ magnétique appliqué était trop faible pour influer sur la polarisation, qui passe de valeurs positives aux basses énergies des électrons à des valeurs négatives pour des énergies plus élevés. Mais, comme les structures hyperfines des niveaux 4 d 2D sont plus faibles, un découplage a été observé, et on a mesuré un accroissement prononcé des raies 5 153 et 5 218 Å (2D3/2-2P1/2 et 2D5/2-2P3/2) quand on passe d'un champ magnétique faible un plus fort. La polarisation atteint sa valeur moyenne entre celles des champs faibles et forts 26 œ pour la raie 5 153 Å et à 11 œ pour la raie 5 218 Å. On discute la polarisation de la raie 5 153 Å par rapport au facteur A et à la durée de vie du niveau 2D3/2 en utilisant la formule de Breit, légèrement modifiée, pour la résonance optique. Le transfert plus important du moment cinétique dans le processus d'excitation rend plus compliqués les calculs de polarisation de la raie 5 218 Å.In an atomic beam experiment Cu atoms being in the 4 s 2S1/2- groundstate were excited by electrons with initial momentum parallel to a static magnetic field. Perpendicular to the electron beam the polarization of spectral lines originating in the 4 p 2P1/2,3/2- et 4 d 2D3/2, 5/2- levels was measured for several energies (< 200 eV) in dependence of the static magnetic field (between 0 and 80 œ). For the 3 273 Å-line (2P1/2-2S1/2) in agreement with theory no polarization was found. Concerning the 3 247 Å-line (2P3/2-2S1/2) the applied magnetic field was to weak to influence the polarization, which changed from positive values at low electron energies to negative values at higher energies. But due to the smaller hfs-splitting of the 4 d 2D-levels decoupling of the hfs was observed and a pronounced increase of the polarization of the 5 153 Å and 5 218 Å line (2D3/2-2P1/2 and 2D5/2-2P3/2) was measured by passing from weak to stronger magnetic fields. The polarization reaches the mean value between the weak and the strong field case at 26 œ for the 5 153 Å-line and at 11 œ for the 5 218 Å line. The polarization of the 5 153 Å line is discussed in terms of the A factor and the lifetime of the 2D3/2- level by use of the slightly modified Breit-formula for resonance scattering of light. Because of the greater angular momentum transfer in the excitation process, calculations concerning the polarization of the 5 218 Å line are more complicated

NUCLEAR QUADRUPOLAR RELAXATION IN LIQUID Ga-Te ALLOYS

The nuclear spin relaxation rate was measured in liquid GacTe1-c alloys on As as an impurity atom. A TDPAD technique was used on the 6 μs 73mAs isomer. The range l≥c≥0.2 was studied, with T=1110 K for c≤0.7. The quadrupolar part of the rate , RQ, was extracted. It shows essentially the same concentration dependence as existing data for RQ of Ga in liquid Gac Tel-c, and correlates strongly with the dip in conductivity near c=0.4. A quantitative analysis of the concentration dependence is attempted using a simple microscopic model. It comprises localization of conduction electrons including one free parameter for charge shift in the Ga-Te bond (ionicity). Satisfactory agreement is obtained

Metrology Light Source The first electron storage ring optimized for generating coherent THz radiation

The Metrology Light Source is a recently constructed 630 MeV electron storage ring, operating as a synchrotron radiation source for the THz to extreme UV spectral range. It is the first storage ring optimized for generating intense, broadband, coherent THz radiation, based on a bunch shortening mode. Stable steady state or bursting THz radiation up to an average power of about 60mW can be obtained. The applied machine operation mode is achieved by manipulating the momentum compaction factor by a novel tuning scheme. The underlying low scheme is of general interest for operating a storage ring in a short bunch mode and is the main subject of this paper. DOI 10.1103 PhysRevSTAB.14.030705 PACS numbers 29.20.db, 41.60.A

RELAXATION OF EXCITED Pb NUCLEI IN LIQUID Hg

On a mesuré l'interaction hyperfine de l'état isomérique (I = 7 ; 2 200 keV) de 206Pb, qui était produit et orienté par la réaction 204Hg (α, 2n), dans Hg liquide. La relaxation quadrupolaire était observée dès 235 K à 528 K. Elle est déterminée par la diffusion ionique.The hyperfine interaction of the I = 7 state of 206Pb at 2 200 keV produced and aligned by the reaction 204Hg (α, 2n), was studied in liquid Hg. The quadrupolar relaxation rate, observed between 235 K and 528 K, is dominated by ionic diffusion