Many observations of molecular lines in interstellar space or planetary atmospheres are affected by serious problems with standing wave patterns in the spectra. This becomes particularly nasty when studying broad extragalactic or pressure broadened atmospheric lines. When observing at THz frequencies these problems become more and more prominent due to the increased required bandwidth. Mostly, such patterns are attributed to reflections in the telescope optics, particularly from the sub-reflector in a Cassegrain telescope. But there are many other sources of standing waves in the quasi-optics of a heterodyne receiver. In this paper we describe the effect of reflections between mixer and local oscillator (LO) inside of a receiver. Some portion of the signal radiation becomes reflected by the mixer, and propagates partly to the LO with reduced amplitude due to the generally small reflectivity of the beam combiner. Nevertheless, although the power in one roundtrip becomes significantly reduced, there is still enough amplitude left, so that interference with the incoming signal radiation becomes visible. The situation is depicted in Fig.1. In the figure the local oscillator and mixer reflectivity is indicated by the power reflection coefficients rL and rM respectively. The beam splitter reflects and transmits the power with coefficients r and t. The field of the LO at the mixer is composed of the superposition of all partial beams which are reflected back and forth between the LO and the mixer. Consequently, after summing up all partial beams, the total LO power coupled to the mixer is: ) ( 0 L L L A P r P ν ⋅ ⋅ = with ( ) 1 2 2 )] / 2 ( sin 4 1 [ ) ( − ⋅ ⋅ ⋅ + − = ν π ν c s u u A PL0 is the power of the LO itself as is incident on the beam splitter, and νL is the LO frequency. A(ν) is the Airy-function as is well known for optical resonators. u = r·√rM·√rL is the roundtrip efficiency for the field amplitude within the cavity, s is the optical path length between mixer and LO, and c is the speed of light.

We irradiated SIS-devices (Superconductor - Insulator - Superconductor) at cryogenic temperature with 50 and 138 MeV proton beams. The total proton fluence reached values up to 5x10(11) p/cm(2). The DC W-curves of the devices were monitored during the experiment. No significant change in the characteristics of the devices was observed.

The present status of AOS development at KOSMA is discussed. A study of a new generation of AOS using the new Bragg-cell material "Rutil" is on the way, which is supposed to lead to spectrometers in the range of 4 GHz total bandwidth at an resolution of 2-3 MHz. A second alternative for a 4 GHz bandwidth spectrometer has been developed as an engineering model for the HIFI instrument aboard the ESA cornerstone mission "Herschel". It consists of an array-AOS with 1 GHz bandwidth of each of the four AOS bands at a resolution of 1 MHz. A hybrid system for an input between 4 and 8 GHz is setup, and various laboratory tests have demonstrated that this system is well suited for large bandwidth applications like with HIFI. For eventual future demand of even larger bandwidth, details of a new optical method for Rf-analysis are discussed. It consists of a modulated laser with one or two Fabry-Perot etalons to analyze the frequency distribution of the resulting laser sidebands. A bandwidth of several, 10 GHz at moderate resolution can be achieved.

An experiment to measure cross sections and both, vector and tensor analyzing powers, for the 1H(d,pp)n breakup reaction at 130 MeV deuteron beam energy is presented. Employing a position-sensitive detection system covering a large solid angle enables probing of a significant part of the whole phase space. First results are presented and compared with the rigorous Faddeev calculations using modern NN and 3NF potentials.

An experiment has been performed at KVI to measure vector analyzing powers and differential cross sections of the D((p) over right arrow pd) reaction as a function of incident beam energy. The measurements have been performed so far at several kinetic energies of the incoming particle between 108 MeV and 170 MeV. In this contribution, the preliminary results for the vector analyzing power A(y) will be presented.

Indications for three nucleon force (3NF) effects in PJd elastic scattering and in specific kinematical configurations of the deuteron breakup reaction became motivation for complex studies of the three nucleon system dynamics in the dp breakup process over a broad region of phase-space. A dedicated experiment is aimed at precise determination of cross sections and both vector and tenser analyzing powers for the H-1((p) over right arrow pp)n breakup reaction at 130 MeV deuteron beam energy. The experiment, employs a position-sensitive detection system covering a large solid angle and allowing for excellent particle identification. The first data taking run has been completed and the accumulated data are being analyzed. The results will be compared with the rigorous calculations within the Faddeev formalism, including various nucleon-nucleon potentials and 3NF models.

A compilation of experimental and theoretical information is presented on the mass 3 systems 3n, 3H, 3He and 3p. Emphasis is on advances since the previous evaluation Tilley et al. (1987) [1987TI07] such as, (1) detailed calculations of the vector and tensor analyzing powers for neutron and proton scattering by deuterium which led to the discovery of the still unresolved analyzing power puzzle, (2) the wide spread use of polarized 3He targets which allowed for the experimental study of sum rules among other things and (3) the ability to include the Coulomb interaction in three-body calculations. As stated in the 1987 evaluation and is still the case, there is no firm evidence for either excited states of 3H or 3He nuclei or for the existence of the trineutron or triproton.

A beam polarimeter for medium-energy protons and deuterons has been constructed. Its operation is based on the elastic-scattering reactions p→+p or d→+p. The outgoing particles are detected in kinematical coincidence in four independent reaction planes, each equipped with two pairs of phoswich detectors.

A series of measurements have been performed at KVI to obtain the vector analyzing power A(y) of the (2)H(p-->,pd) reaction as a function of incident beam energy at energies of 120, 135, 150, and 170 MeV. For all these measurements, a range of theta(c.m.) from 30 degrees to 170 degrees has been covered. The purpose of these investigations is to observe possible spin-dependent effects beyond two-nucleon forces. When compared to the predictions of Faddeev calculations, based on two-nucleon forces only, significant deviations are observed at all energies and at center-of-mass angles between 70 degrees and 130 degrees. The addition of present-day three-nucleon forces does not improve the description of the data, demonstrating the still insufficient understanding of the properties of three-nucleon systems.

New vector analyzing-power data on (p) over right arrow+ d elastic scattering at E-p = 150 and 190 MeV have been measured. These an presented together with existing data and with recent (d) over right arrow + p vector and tensor analyzing power data at E-d = 270 MeV. The strong negative extremum of both vector analyzing powers A(y)(p) and A(y)(d) at theta(c.m.) similar or equal to 80 degrees-120 degrees is underestimated by Faddeev calculations using modern NN forces. Inclusion of the Tucson-Melbourne 3N force shifts the minima upwards, but with conflicting results for p A(y)(p), and leading to a good description for A(y)(d). An A(y)(p) puzzle, previously thought to exist at energies E-N less than or equal to 30 MeV only, appears to exist also at intermediate energies.

New vector analyzing-power data on $\stackrel{\ensuremath{\rightarrow}}{p}+d$ elastic scattering at ${E}_{p}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}150$ and $190\mathrm{MeV}$ have been measured. These are presented together with existing data and with recent $\stackrel{\ensuremath{\rightarrow}}{d}+p$ vector and tensor analyzing power data at ${E}_{d}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}270\mathrm{MeV}$. The strong negative extremum of both vector analyzing powers ${A}_{y}^{p}$ and ${A}_{y}^{d}$ at ${\ensuremath{\theta}}_{\mathrm{c}.\mathrm{m}.}\ensuremath{\simeq}80\ifmmode^\circ\else\textdegree\fi{}--120\ifmmode^\circ\else\textdegree\fi{}$ is underestimated by Faddeev calculations using modern $\mathrm{NN}$ forces. Inclusion of the Tucson-Melbourne $3N$ force shifts the minima upwards, but with conflicting results for ${A}_{y}^{p}$, and leading to a good description for ${A}_{y}^{d}$. An ${A}_{y}^{p}$ puzzle, previously thought to exist at energies ${E}_{N}\ensuremath{\le}30\mathrm{MeV}$ only, appears to exist also at intermediate energies.

A beam-polarimeter for medium energy protons and deuterons (E=100-200 MeV) has been constructed. Its operation is based on the p + d, p + p and d + p elastic scattering with coincident detection of both particles in 4 independent planes. The 16 detectors of the Polarimeter have a phoswich construction to ensure particle identification. With this device the analyzing power, A y , of p + d elastic scattering has been measured at 190 MeV for CM- angles of 25° to 115° in two planes, monitored by p+ p elastic scattering in the two other planes. The target was mixed CH2/CD2. This allowed for simultaneous extraction of A y (p,d) and the beam polarizations. The analyzing power is compared with calculations based on the Bonn-potential including partial waves up to J = 5.

The 37Ar(n_th,alpha)34S and 37Ar(n_th,p)37Cl reactions were studied at the high flux reactor of the ILL in Grenoble. For the 37Ar(n_th,alpha_0) and 37Ar(n_th,p) reaction cross sections, values of (1070+/-80)b and (37+/-4)b, respectively, were obtained. Both values are about a factor 2 smaller than results of older measurements. The observed suppression of the 37(n_th,alpha_1) transition could be verified from theoretical considerations. Finally, evidence was found for the two-step 37Ar(n_th,gamma-alpha) process.