An ionization chamber shower detector for the LHC luminosity monitor

Beche, J.-F.; Burks, M.; Datte, P.; Haguenauer, M.; Manfredi, P. F.; Millaud, J.; Placidi, M.; Ratti, L.; Re, V.; Riot, Vincent; Schmickler, H.; Speziali, V.; Turner, W.C.

doi:10.1109/tns.2002.998655

Cited by 5 publications

(8 citation statements)

References 4 publications

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“…The less than linear increase above 600kPa corresponds to the drift velocity falling below the saturation value 3.2cm/µs for E/p<1,000V/cm-atm. [6]. In Fig.…”

Section: ) Pulse Height and Fwhm Versus Gas Pressurementioning

confidence: 98%

“…The instrumentation would be used as a storage ring operations tool to keep the LHC operating near optimum luminosity. The first beam test results showed sensitivity to showers initiated by single protons, linearity of signal with ionization chamber pressure and location of shower maximum at the anticipated thickness of absorber (~20cm of iron) [6]. Two issues were identified which required further development: (1) reduction of capacitive noise coupling between quadrants and (2) reduction of pulse width and improvement of pulse shape.…”

Section: Introductionmentioning

confidence: 99%

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Initial test results of an ionization chamber shower detector for a LHC luminosity monitor

Datte

Beche

Haguenauer

et al. 2003

IEEE Trans. Nucl. Sci.

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Abstract-A novel segmented, multi-gap, pressurized gas ionization chamber is being developed for optimization of the luminosity of the LHC. The ionization chambers are to be installed in the front quadrupole and zero degree neutral particle absorbers in the high luminosity IRs and sample the energy deposited near the maxima of the hadronic/electromagnetic showers in these absorbers. The ionization chambers are instrumented with low noise, fast, pulse shaping electronics to be capable of resolving individual bunch crossings at 40MHz. In this paper we report the initial results of our second test of this instrumentation in an SPS external proton beam. Single 300GeV protons are used to simulate the hadronic/electromagnetic showers produced by the forward collision products from the interaction regions of the LHC. The capability of instrumentation to measure the luminosity of individual bunches in a 40MHz bunch train is demonstrated.

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“…The less than linear increase above 600kPa corresponds to the drift velocity falling below the saturation value 3.2cm/µs for E/p<1,000V/cm-atm. [6]. In Fig.…”

Section: ) Pulse Height and Fwhm Versus Gas Pressurementioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Initial test results of an ionization chamber shower detector for a LHC luminosity monitor

Datte

Beche

Haguenauer

et al. 2003

IEEE Trans. Nucl. Sci.

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“…To provide fast charge collection and for signal to noise considerations in the presence of a cable, the detector is configured with 60 gaps 0.5mm gaps connected 10 in parallel and 6 series connections [1]. This connection provides an equivalent detector capacitance of 50pF as seen by the amplifier.…”

Section: Gap Connectionsmentioning

confidence: 99%

“…It is inversely proportional to the capacitance of the gap ( gap C ) and the square of the ballistic factor (σ ~ 2.8) that describes the reduction in signal due to clipping. This is the ratio of the electron charge transfer time (~ 20ns), to the shaping time (τ ~ 2ns) of the amplifier [1].…”

Section: Gap Connectionsmentioning

confidence: 99%

“…The frequency response of the termination is made by implementing a high frequency bipolar transistor (Siemens BFP 540) and paralleled by 4 to reduce the base spreading resistance R bb ' [1]. This device has a larger transition frequency and a slightly smaller base spreading resistance when compared to the transistor employed in the previous amplifier version that used the NEC 856 [1].…”

Section: Active Terminationmentioning

confidence: 99%

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Electrical design considerations for a 40 MHz gas ionization chamber

Datte

Manfredi

Millaud

et al. 2001

PACS2001. Proceedings of the 2001 Particle Accelerator Conference (Cat. No.01CH37268)

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The front IR quadrupole absorbers (TAS) and the IR neutral particle absorbers (TAN) in the high luminosity insertions of the Large Hadron Collider (LHC) each absorb approximately 1.8 TeV of forward collision products on average per pp interaction (~235W at design luminosity 10 34 cm -2 s -1 ). This secondary particle flux can be exploited to provide a useful storage ring operations tool for optimization of luminosity. A novel segmented, multi-gap, pressurized gas ionization chambers is being developed for sampling the energy deposited near the maxima of the hadronic/ electromagnetic showers in these absorbers. The ionization chamber must be capable of resolving individual bunch crossings at 40MHz. The ionization chamber is segmented into quadrants; each quadrant consists of sixty (40x40)mm 2 Cu plates 1.0mm thick, with 0.5mm gaps. The 0.5mm gap width has been chosen so that the time for the ionization electrons to drift across the gap, is short enough to produce at the out put of the shaping amplifier, a signal that returns to the base line is less than the 25ns bunch spacing of the LHC. From noise considerations in the presence of a cable the stack of plates are connected electrically 10 in parallel, 6 in series to achieve an equivalent detector capacitance C d~5 0pF. This type connection forms an electrode inductive L e and electrode capacitive C e network that must be optimized to transfer charge from the chamber to the sensing amplifier. This paper describes the design of the collection electrodes optimized for 40 MHz operation.

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The BRAN luminosity detectors for the LHC

Placidi

Ratti

Turner

et al. 2017

Nuclear Instruments and Methods in Physics Research Section A:

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A B S T R A C TThis paper describes the several phases which led, from the conceptual design, prototyping, construction and tests with beam, to the installation and operation of the BRAN (Beam RAte of Neutrals) relative luminosity monitors for the LHC. The detectors have been operating since 2009 to contribute, optimize and maintain the accelerator performance in the two high luminosity interaction regions (IR), the IR1 (ATLAS) and the IR5 (CMS). The devices are gas ionization chambers installed inside a neutral particle absorber 140 m away from the Interaction Points in IR1 and IR5 and monitor the energy deposited by electromagnetic showers produced by high-energy neutral particles from the collisions. The detectors have the capability to resolve the bunch-bybunch luminosity at the 40 MHz bunch rate, as well as to survive the extreme level of radiation during the nominal LHC operation. The devices have operated since the early commissioning phase of the accelerator over a broad range of luminosities reaching 1.4×10 34 cm −2 s −1 with a peak pileup of 45 events per bunch crossing. Even though the nominal design luminosity of the LHC has been exceeded, the BRAN is operating well.After describing how the BRAN can be used to monitor the luminosity of the collider, we discuss the technical choices that led to its construction and the different tests performed prior to the installation in two IRs of the LHC. Performance simulations are presented together with operational results obtained during p-p operations, including runs at 40 MHz bunch rate, Pb-Pb operations and p-Pb operations.

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An ionization chamber shower detector for the LHC luminosity monitor

Cited by 5 publications

References 4 publications

Initial test results of an ionization chamber shower detector for a LHC luminosity monitor

Initial test results of an ionization chamber shower detector for a LHC luminosity monitor

Electrical design considerations for a 40 MHz gas ionization chamber

The BRAN luminosity detectors for the LHC

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