HB2012 - List of Authors (Lechner, A.)

Paper

Title

Page

Bunch-by-Bunch Beam Loss Diagnostics with Diamond Detectors at the LHC

41

M. Hempel
BTU, Cottbus, Germany
T. Baer
University of Hamburg, Hamburg, Germany
S. Bart Pedersen, B. Dehning, E. Effinger, E. Griesmayer, A. Lechner, R. Schmidt
CERN, Geneva, Switzerland
W. Lohmann
DESY, Hamburg, Germany

A main challenge in the operation with high intensity beams is managing beam losses that imply the risk of quenching superconducting magnets or even damage equipment. There are various sources of beam losses, such as losses related to injection, to beam instabilities and to UFOs (Unidentified Falling Objects). Mostly surprising in the first years of LHC operation was the observation of UFOs. They are believed to be dust particles with a typical size of 1-100 um, which lead to beam losses with a duration of about ten revolutions when they fall into the beam. 3600 BLMs (Beam Loss Monitors) are installed around the LHC ring, allowing to determinate the accurate location of UFOs. The time resolution of the BLMs is 40 us (half a turn revolution). A measurement of the beam losses with a time resolution better than the bunch spacing of 50 ns is crucial to understand loss mechanisms. Diamond sensors are able to provide such diagnostics and perform particle counting with ns time resolution. In this paper, we present measurements of various types of beam losses with diamond detectors. We also compare measurements of UFO induced beam losses around the LHC ring with results from MadX simulations.

TUO1C04

Detection of Unidentified Falling Objects at LHC

305

E. Nebot Del Busto, T. Baer, F.V. Day, B. Dehning, E.B. Holzer, A. Lechner, R. Schmidt, J. Wenninger, C. Zamantzas, M. Zerlauth, F. Zimmermann
CERN, Geneva, Switzerland
M. Hempel
BTU, Cottbus, Germany

About 3600 Ionization Chambers are located around the LHC ring to detect beam losses that could damage the equipment or quench superconducting magnets. The BLMs integrate the losses in 12 different time intervals (from 40 μs to 83.8 s) allowing for different abort thresholds depending on the duration of the loss and the beam energy. The signals are also recorded in a database at 1 Hz for offline analysis. Since the 2010 run, a limiting factor in the machine availability occurred due to unforeseen sudden losses appearing around the ring on the ms time scale. Those were detected exclusively by the BLM system and they are the result of the interaction of macro-particles, of sizes estimated to be 1-100 microns, with the proton beams. In this document we describe the techniques employed to identify such events as well as the mitigations implemented in the BLM system to avoid unnecessary LHC downtime.

Slides TUO1C04 [6.812 MB]

Paper	Title	Page
MOP203	Bunch-by-Bunch Beam Loss Diagnostics with Diamond Detectors at the LHC	41
	M. Hempel BTU, Cottbus, Germany T. Baer University of Hamburg, Hamburg, Germany S. Bart Pedersen, B. Dehning, E. Effinger, E. Griesmayer, A. Lechner, R. Schmidt CERN, Geneva, Switzerland W. Lohmann DESY, Hamburg, Germany
	A main challenge in the operation with high intensity beams is managing beam losses that imply the risk of quenching superconducting magnets or even damage equipment. There are various sources of beam losses, such as losses related to injection, to beam instabilities and to UFOs (Unidentified Falling Objects). Mostly surprising in the first years of LHC operation was the observation of UFOs. They are believed to be dust particles with a typical size of 1-100 um, which lead to beam losses with a duration of about ten revolutions when they fall into the beam. 3600 BLMs (Beam Loss Monitors) are installed around the LHC ring, allowing to determinate the accurate location of UFOs. The time resolution of the BLMs is 40 us (half a turn revolution). A measurement of the beam losses with a time resolution better than the bunch spacing of 50 ns is crucial to understand loss mechanisms. Diamond sensors are able to provide such diagnostics and perform particle counting with ns time resolution. In this paper, we present measurements of various types of beam losses with diamond detectors. We also compare measurements of UFO induced beam losses around the LHC ring with results from MadX simulations.

TUO1C04	Detection of Unidentified Falling Objects at LHC	305
	E. Nebot Del Busto, T. Baer, F.V. Day, B. Dehning, E.B. Holzer, A. Lechner, R. Schmidt, J. Wenninger, C. Zamantzas, M. Zerlauth, F. Zimmermann CERN, Geneva, Switzerland M. Hempel BTU, Cottbus, Germany
	About 3600 Ionization Chambers are located around the LHC ring to detect beam losses that could damage the equipment or quench superconducting magnets. The BLMs integrate the losses in 12 different time intervals (from 40 μs to 83.8 s) allowing for different abort thresholds depending on the duration of the loss and the beam energy. The signals are also recorded in a database at 1 Hz for offline analysis. Since the 2010 run, a limiting factor in the machine availability occurred due to unforeseen sudden losses appearing around the ring on the ms time scale. Those were detected exclusively by the BLM system and they are the result of the interaction of macro-particles, of sizes estimated to be 1-100 microns, with the proton beams. In this document we describe the techniques employed to identify such events as well as the mitigations implemented in the BLM system to avoid unnecessary LHC downtime.
	Slides TUO1C04 [6.812 MB]