Belle II Vertex Detector Performance

The Belle II experiment at the SuperKEKB accelerator (KEK, Tsukuba, Japan) collected its first e+e− collision data in the spring 2019. The aim of accumulating a 50 times larger data sample than Belle at KEKB, a first generation B-Factory, presents substantial challenges to both the collider and the detector, requiring not only state-of-the-art hardware, but also modern software algorithms for tracking and alignment. The broad physics program requires excellent performance of the vertex detector, which is composed of two layers of DEPFET pixels and four layers of double sided-strip sensors. In this contribution, an overview of the vertex detector of Belle II and our methods to ensure its optimal performance, are described, and the first results and experiences from the first physics run are presented

MADMAX Status Report

In this report we present the status of the MAgnetized Disk and Mirror Axion eXperiment (MADMAX), the first dielectric haloscope for the direct search of dark matter axions in the mass range of 40 to 400 $\mu$eV. MADMAX will consist of several parallel dielectric disks, which are placed in a strong magnetic field and with adjustable separations. This setting is expected to allow for an observable emission of axion induced electromagnetic waves at a frequency between 10 and 100 GHz corresponding to the axion mass. The present document orignated from a status report to the DESY PRC in 2019

Usage of the CERN MORPURGO magnet for the MADMAX prototype

The MAgnetized Disk and Mirror Axion eXperiment (MADMAX) is a new initiative to search for dark matter axions in the mass range of 40 to 400 $\mu$eV. The MADMAX collaboration is presently preparing its prototype booster to validate the experimental concept by proving the mechanical feasibility. Here we propose to use the MORPURGO magnet at CERN during SPS shutdown periods to demonstrate the mechanical feasibility of the concept in an external static B-field. Additionally, the MORPURGO magnet would be used to perform a first competitive search for ALPs in a so far unexplored parameter range

Usage of the CERN MORPURGO magnet for the MADMAX prototype April 2020 MADMAX prototype

The MAgnetized Disk and Mirror Axion eXperiment (MADMAX) is a new initiative to search for dark matter axions in the mass range of 40 to 400 μeV. The MADMAX collaboration is presently preparing its prototype booster to validate the experimental concept by proving the mechanical feasibility. Here we propose to use the MORPURGO magnet at CERN during SPS shutdown periods to demonstrate the mechanical feasibility of the concept in an external static B-field. Additionally, the MORPURGO magnet would be used to perform a first competitive search for ALPs in a so far unexplored parameter range

MADMAX Status Report

In this report we present the status of the MAgnetized Disk and Mirror Axion eXperiment (MADMAX), the first dielectric haloscope for the direct search of dark matter axions in the mass range of 40 to 400 $\mu$eV. MADMAX will consist of several parallel dielectric disks, which are placed in a strong magnetic field and with adjustable separations. This setting is expected to allow for an observable emission of axion induced electromagnetic waves at a frequency between 10 and 100 GHz corresponding to the axion mass. The present document orignated from a status report to the DESY PRC in 2019

DEPFET pixel detector in the Belle II experiment

The Belle II experiment will run with a reduced beam asymmetry and a factor of 40 higher instantaneous luminosity compared to the Belle experiment. To cope with this and to be able to perform high precision vertex measurements for charge conjugation parity violating processes, a pixel detector based on DEPFET technology will be installed in the center of Belle II. Its basic properties and the DAQ chain are presented in this article

Belle II pixel detector: Performance of final DEPFET modules

A DEpleted P-channel Field Effect Transistor (DEPFET) based pixel detector was developed for the Belle II VerteX Detector (VXD). It is designed to achieve a good impact parameter resolution better than 15μm at the very high luminosity conditions of this experiment. In the first half of 2018 four final production modules have been deployed in the commissioning run of the detector and their performance is discussed

Operational experience of the Belle II pixel detector

The Belle II experiment at the SuperKEKB accelerator has started its physics data taking with the full detector setup in March 2019. It aims to collect 40 times more e+e− collision data compared with its predecessor Belle experiment. The Belle II pixel detector (PXD) is based on the Depleted P-channel Field Effect Transistor (DEPFET) technology. The PXD plays an important role in the tracking and vertexing of the Belle II detector. Its two layers are arranged at radii of 14 mm and 22 mm around the interaction point. The sensors are thinned down to 75 μm to minimize multiple scattering, and each module has interconnects and ASICs integrated on the sensor with silicon frames for mechanical support. PXD showed good performance during data taking. It also faces several operational challenges due to the high background level from the SuperKEKB accelerator, such as the damage from beam loss events, the drift in the HV working point due to radiation effect, and the impact of the high background

Operational Experience and Performance of the Belle II Pixel Detector

The Belle II experiment at the super KEK B factory (SuperKEKB) started its physics operation with the full detector setup in March 2019, and it aims at collecting 50 ab$^{−1}$ of $e^+e^−$ collision data. The vertex detector (VXD) of Belle II contains a 4-layer silicon vertex detector (SVD) using double sided silicon strips and an inner 2-layer pixel detector (PXD) that is based on the depleted P-channel Field Effect Transistor (DEPFET) technology. The signal generation and amplification are combined in pixels with a minimum pitch of 55 × 50 µm$^2$. The sensors are thinned down to 75 µm, and each module has interconnects and ASICs integrated on the sensor with silicon frames for mechanical support. This approach led to a material budget of around 0.21% X$_0$ per layer including the cooling structure in the acceptance region. The PXD has an integration time of around 20 µs, a signal-to-noise ratio of around 50 and a detecting efficiency of better than 99%. Its two layers are arranged at the radii of 14 and 22 mm around the interaction point, and an impact parameter resolution of better than 15 µm has been achieved. Due to its close proximity to the beam line and its sensitivity to few-keV photons, the PXD also plays an important role in background studies