Photon collimator system for the ILC Positron Source

High energy e+e- linear colliders are the next large scale project in particle physics. They need intense sources to achieve the required luminosity. In particular, the positron source must provide about 10E+14 positrons per second. The positron source for the International Linear Collider (ILC) is based on a helical undulator passed by the electron beam to create an intense circularly polarized photon beam. With these photons a longitudinally polarized positron beam is generated; the degree of polarization can be enhanced by collimating the photon beam. However, the high photon beam intensity causes huge thermal load in the collimator material. In this paper the thermal load in the photon collimator is discussed and a flexible design solution is presented.Comment: 22 pages, 19 figures, 8 tables, cross-reference to table 4 fixe

Femtosecond dynamics snapshots of the early ion track evolution

The energy dissipation and femtosecond dynamics due to fast heavy ions in matter is critically reviewed with emphasis on possible mechanisms that lead to materials modi cations. Starting from a discussion of the initial electronic energy deposition processes, three basic mechanisms for the conversion of electronic into atomic energy are investigated by means of Auger electron spectroscopy. Results for amorphous Si, amorphous C and polypropylene are presented and discussed. Experimental evidence for a highly charged track region as well as for hot electrons inside tracks is shown. As follows mainly from Auger electron spectroscopy, there are strong indications for di erent track production mechanisms in di erent material

Search for short time phase effects in the electronic damage evolution A case study with silicon

This work focusses on the production and decay properties of inner shell vacancies and valence band excitations induced by swift highly charged ions interacting with amorphous and crystalline Si. High resolution electron spectra have been taken for fast heavy ions at 1.78 5 MeV u as well as for electrons of similar velocity incident on atomically clean Si targets of well defined phase. Various Augerelectron structures are analyzed concerning their width, their intensity and exact peak position. All measured peaks show a small shift towards lower energy when the charge of the projectile is increased. This finding is an indication for a nuclear track potential inside the ion track. A detailed analysis of the Auger electron spectra for amorphous Si and crystalline Si 111 7 x 7 points to a small but significant phase effect in the short time dynamics of ion track

Design of Pre-Dumping Ring Spin Rotator with a Possibility of Helicity Switching for Polarized Positrons at the ILC

The use of polarized beams enhance the possibility of the precision measurements at the International Linear Collider (ILC). In order to preserve the degree of polarization during beam transport spin rotators are included in the current TDR ILC Lattice. In this report some advantages of using a combined spin rotator/spin flipper are discussed. A few possible lattice designs of spin flipper developed at DESY in 2012 are presented.Comment: Talk presented at the International Workshop on Future Linear Colliders (LCWS15), Whistler, Canada, 2-6 November 201

Index

Transgenic APP23 mice were generated to model Alzheimer's disease. The APP23 model develops pathological features, learning deficits, and memory deficits analogous to dementing patients. In this report, transgenic mice exhibited several behavioral disturbances indicating the presence of neuropsychiatric symptoms of dementia. Aiming to verify whether the model also develops other behavioral problems, the authors investigated ingestive behavior in APP23 males of 3, 6 and 12 months. In addition, body weights of a naive male group were longitudinally monitored starting at weaning. Olfactory acuity was evaluated in mice of different age groups. Although olfactory functioning of APP23 mice appeared intact, they drank more and took more food pellets compared with wild-type littermates during a 1-week registration period. From the age of 4.5 weeks onward, APP23 males weighed significantly less than their control littermates, whereas this difference became more prominent with increasing age. Our results suggest the presence of a hypermetabolic state in this model. This is the first report, evidencing the presence of changes in eating and drinking behavior in a single transgenic Alzheimer mouse model.status: publishe

Memory deficits in APP23/Abca1+/− mice correlate with the level of Aβ oligomers

ABCA1, a member of the ATP-binding cassette family of transporters, lipidates ApoE (apolipoprotein A) and is essential for the generation of HDL (high-density lipoprotein)-like particles in the CNS (central nervous system). Lack of Abca1 increases amyloid deposition in several AD (Alzheimer's disease) mouse models. We hypothesized that deletion of only one copy of Abca1 in APP23 (where APP is amyloid precursor protein) AD model mice will aggravate memory deficits in these mice. Using the Morris Water Maze, we demonstrate that 2-year-old Abca1 heterozygous APP23 mice (referred to as APP23/het) have impaired learning during acquisition, and impaired memory retention during the probe trial when compared with age-matched wild-type mice (referred to as APP23/wt). As in our previous studies, the levels of ApoE in APP23/het mice were decreased, but the differences in the levels of Aβ and thioflavin-S-positive plaques between both groups were insignificant. Importantly, dot blot analysis demonstrated that APP23/het mice have a significantly higher level of soluble A11-positive Aβ (amyloid β protein) oligomers compared with APP23/wt which correlated negatively with cognitive performance. To confirm this finding, we performed immunohistochemistry with the A11 antibody, which revealed a significant increase of A11-positive oligomer structures in the CA1 region of hippocampi of APP23/het. This characteristic region-specific pattern of A11 staining was age-dependent and was missing in younger APP23 mice lacking Abca1. In contrast, the levels of Aβ*56, as well as other low-molecular-mass Aβ oligomers, were unchanged among the groups. Overall, the results of the present study demonstrate that in aged APP23 mice memory deficits depend on Abca1 and are likely to be mediated by the amount of Aβ oligomers deposited in the hippocampus

Ultrafast electronic processes in an insulator The Be and O sites in BeO

The short time dynamics of amorphous beryllium oxide a BeO has been investigated for electronic excitation ionization by fast incident electrons, as well as by Ar7 , Ar15 , Xe15 , and Xe31 ions at velocities of 6 10 the speed of light. Site specific Auger electron spectra induced by fast heavy ions are the central point of this investigation. Electron induced Auger spectra serve as a reference and electron energy loss EELS spectroscopy as well as resonant inelastic X ray scattering RIXS are invoked for quantitative understanding. For the heavy ion case, we observe strong variations in the corresponding spectral distributions of Be K and O K Auger lines. These are related to local changes of the electron density, of the electron temperature and even of the electronic band structure of BeO on a femtosecond time scale after the passage of highly charged heavy ions