Ryan Page

The LCFIVertex package: vertexing, flavour tagging and vertex charge reconstruction with an ILC vertex detector

The precision measurements envisaged at the International Linear Collider (ILC) depend on excellent instrumentation and reconstruction software. The correct identification of heavy flavour jets, placing unprecedented requirements on the quality of the vertex detector, will be central for the ILC programme. This paper describes the LCFIVertex software, which provides tools for vertex finding and for identification of the flavour and charge of the leading hadron in heavy flavour jets. These tools are essential for the ongoing optimisation of the vertex detector design for linear colliders such as the ILC. The paper describes the algorithms implemented in the LCFIVertex package as well as the scope of the code and its performance for a typical vertex detector design.

Development of the kaon tagging system for the NA62 experiment at CERN

The NA62 experiment at CERN aims to make a precision measurement of the ultra-rare decay K+→π+νν¯, and relies on a differential Cherenkov detector (KTAG) to identify charged kaons at an average rate of 50 MHz in a 750 MHz unseparated hadron beam. The experimental sensitivity of NA62 to K-decay branching ratios (BR) of 10−11 requires a time resolution for the KTAG of better than 100 ps, an efficiency better than 95% and a contamination of the kaon sample that is smaller than 10−4. A prototype version of the detector was tested in 2012, during the first NA62 technical run, in which the required resolution of 100 ps was achieved and the necessary functionality of the light collection system and electronics was demonstrated.

Using a Monolithic Active Pixel Sensor for Monitoring Multileaf Collimator Positions in Intensity Modulated Radiotherapy

To enable in-vivo monitoring of Intensity Modulated Radiotherapy (IMRT) with minimal attenuation of the treatment field, an upstream camera system based on a Monolithic Active Pixel Sensor (MAPS) has been developed. This system has been used to precisely reconstruct the position of the Multileaf Collimators (MLC) that are used to shape the treatment field. The results show the position of a MLC is known with a precision of 6 μm with 10 seconds worth of data and 52 ±4 μm for a single frame.

First radiation hardness results of the TeraPixel Active Calorimeter (TPAC) sensor

The TeraPixel Active Calorimeter (TPAC) sensor is a novel Monolithic Active Pixel Sensors (MAPS) device developed for use as the active layers of a large area, digital electromagnetic calorimeter (DECAL) at a future e+e− collider. Further applications, which include the tracking and vertex systems for future lepton colliders and LHC upgrades have been proposed and it is therefore essential to characterise the behaviour of the sensor for these applications. We present the first studies of radiation hardness testing of the TPAC sensor. The performance of the sensor has been evaluated after exposures up to 5 Mrad of 50 keV x-rays. Under realistic ILC operating conditions a maximum decrease in the signal to noise ratio of 8% (15%) was observed after 200 krad (5 Mrad) which is already sufficient for proposed applications in future e+e− colliders.

Towards using a Monolithic Active Pixel Sensor for in-vivo beam monitoring of Intensity Modulated Radiotherapy

To enable in-vivo monitoring of Intensity Modulated Radiotherapy (IMRT) with minimal attenuation of the treatment field, an upstream camera system based on a Monolithic Active Pixel Sensor (MAPS) has been developed. This system has been used to precisely reconstruct the position of the Multileaf Collimators (MLC) that are used to shape the treatment field. The results show the position of a MLC is known with a precision of 6 μm with 10 seconds worth of data and 52 ± 4 μm for a single frame.

Beam test results of FORTIS, a 4T MAPS sensor with a signal-to-noise ratio exceeding 100

We have tested the first 4T Monolithic Active Pixel Sensor (MAPS) for particle physics, FORTIS in a beam test. We have measured a signal-to-noise ratio of more than 100 for MIPs due to the excellent noise performance of the 4T architecture. Two versions of the sensor were tested; with and without deep P-well areas in-pixel. The deep P-well areas allow the incorporation of PMOS transistors inside the pixels without signal charge loss. The measured position resolutions were around 2 μm.

Toward Pulse by Pulse Dosimetry Using an SC CVD Diamond Detector

Solid state detectors with nanosecond response times to incoming radiation are increasingly present at the forefront of radiotherapy dosimetry research. The fast response time of materials, such as diamond, allow pulse by pulse dosimetry. There is a trend in radiotherapy to move toward shorter treatments, using fewer but more intense pulses with varying pulse rates and intensities. This makes the possibility of measuring individual pulses very attractive and would allow intervention during the treatment and not just afterwards. Here, an analogue front end has been developed and combined with a chemical vapor deposition diamond detector to provide real time, pulse by pulse beam intensity measurements. The front end design is discussed and the experimental results obtained using a medical linear accelerator are presented. The results show that the device is capable of pulse by pulse beam intensity measurements up to pulse rates well above 1 kHz. The system performs so well that its variations are negligible compared to the pulse to pulse intensity variations. The dosimetric performance of our system was compared to a commercially available, integrating diamond detector, the microDiamond by PTW. The dose and dose-rate linearity of our system is comparable with the one of the microDiamond and has the additional advantage of being able to measure the deposited dose per pulse.