AIDA-2020-POSTER-2016-002 AIDA-2020 Advanced European Infrastructures for Detectors at Accelerators Poster The Beam Profile Monitoring System for the CERN IRRAD Proton Facility F. Ravotti (CERN) 11 September 2016 The AIDA-2020 Advanced European Infrastructures for Detectors at Accelerators project has received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement no. 654168. This work is part of AIDA-2020 Work Package 15: Upgrade of beam and irradiation test infrastructure. The electronic version of this AIDA-2020 Publication is available via the AIDA-2020 web site <http://aida2020.web.cern.ch> or on the CERN Document Server at the following URL: <http://cds.cern.ch/search?p=AIDA-2020-POSTER-2016-002> Copyright c CERN for the benefit of the AIDA-2020 Consortium
Transcript
AIDA-2020-POSTER-2016-002
AIDA-2020Advanced European Infrastructures for Detectors at Accelerators
Poster
The Beam Profile Monitoring System forthe CERN IRRAD Proton Facility
F. Ravotti (CERN)
11 September 2016
The AIDA-2020 Advanced European Infrastructures for Detectors at Accelerators projecthas received funding from the European Union’s Horizon 2020 Research and Innovation
programme under Grant Agreement no. 654168.
This work is part of AIDA-2020 Work Package 15: Upgrade of beam and irradiation testinfrastructure.
The electronic version of this AIDA-2020 Publication is available via the AIDA-2020 web site<http://aida2020.web.cern.ch> or on the CERN Document Server at the following URL:
ABSTRACTIn particle physics experiments, devices are frequently required to withstand a certain radiation level. As a result, detectors and electronics must be irradiated to determine their level of radiation tolerance. To perform theseirradiations, CERN built a new Irradiation Facility in the East experimental area at the Proton Synchrotron (PS) accelerator. At this facility, named IRRAD, a high-intensity 24 GeV/c proton beam is used to irradiate samples. During theirradiation it is necessary to monitor the intensity and the transverse profile of the beam as it irradiates devices. The PS East Area Irradiation Facility beam profile monitor (BPM) uses 39-channel pixel detectors to monitor the beamposition. These pixel detectors, that must withstand high cumulated radiation levels, are constructed using thin foil copper pads positioned on a flex circuit. When protons pass through the copper pads, they induce a measurablecurrent. To measure this current and determine the total flux of protons passing through the thin foil copper detectors, a new data acquisition system was designed as well as a new database and on-line display system. In its finalconfiguration, the IRRAD facility exploits 4 “main” BPM devices located along the path of the irradiation beam.
In this work, we present the design and the architecture of the BPM system, some results on its performance with the IRRAD proton beam, as well as its ongoing upgrades.
SEE from Thin Metal Foils: Choice of the Detector Material
The need for an on-line method to determine the position andthe profile of the IRRAD proton beam motivated a feasibilitystudy of an instrument based on the proton-induced SecondaryElectron Emission (SEE) from thin metal foils. The foils arerequired to be made of a low cost and relatively short radio-activity lifetime material. Moreover they have to be on the onehand thin to avoid scattering of beam but on the other handthick enough to allow easy handling. Finally, the material hasto show an SEE yield strong enough to avoid the usage of aexternal bias in the IRRAD beam and thus maintain thesimplest operation principle as possible. The BPM test setup consisted of a 3x3 cm2, 100µm thick
Al foil mounted transversally on the IRRAD proton beam. At a fixed vertical position the foil was displaced to
different horizontal positions and the charge integrated.
15 meterstime ~ 450 ms
(PS proton extraction)
Signal (V) ~ 250 mV at center of beam spot.
S/N = 5
Amplifier45 pA/V
t (50 ms/div)
BPM Test Setup V (50 mV/div)
Beam Profile Monitor (BPM) Hardware
39 separate 4x4mm2 pads (beam profile) 0.5mm spacing between pads covers a 36mm x 27mm (x,y) area 6 layer Kapton/Cu flex circuit
‒ top and bottom layer shields‒ pads on internal layers connected
through vias pad thickness (Cu) 1.75μm / layer Kapton thickness 120μm / layer overall thickness ~700μm 1 single 5x5mm2 pad
(irradiation systems alignment)
BPM 4
Detectors
Data Acquisition System
BPM 3
BPM 2 BPM 1
single padLocation of multi-pads BPM detectors in IRRAD
Multi & single BPM detectors
DAQ Controlled by Arduino Yún
Communication over Ethernet
Time handling for DAQ
50 Channels‒ 40 channels via a 20 meter micro-
coaxial cable to the BPM detector (up to 35m)
‒ 10 channels (auxiliary LEMOs on the front panel) to readout the single pad detectors
System installed next to the PS timing distribution Local Server collect and send data to ORACLE Database
‒Beam positions are recorded for later analysis Real time information displayed on a web-page and used by:
‒ IRRAD OP team and users to check beam quality and alignment of irradiation systems
‒PS operation team at CERN Control Center (CCC) to tune the T8 beam
Total proton flux through irradiated samples can be estimated using only the BPM data
‒ linear behaviour BPM signal vs. beam intensity
System Architecture
BPM rack IRRAD and PS timing
distribution
PAD intensities
DAQ System TimingSecondary Emission Chamber
(PS Beam Instrumentation)
Integral of BPM Pads SignalBPM Voltage vs. SEC counts
www.cern.ch/opwt/irrad
BPM Display Page
Horizontal and Vertical Beam Profiles
Summary Page containing all BPM
detectors
“reply” function allow to display the beam profile data archived in the ORACLE DB
Beam Intensities from both multi- pads and
single pad BPM detectors
The single pad BPM detectors are used during IRRAD operation to monitor on-line the position of the irradiation equipment
The summary page allows the simultaneous monitoring of the beam position along the IRRAD facility (beam steering)
BPM “all” Page
Beam Intensity Page
Longitudinal profile (integral)
The East Area contains 4 beam lines: T8, T9, T10 and T11. The beam lines are derived from the24GeV/c primary beam of the PS, which provides 2.4s cycles with a flat top of about 400ms. Somecycles serve the North target (for T9, T10 and T11), some the South branch (for T8)
T8
East Area Facility Access Point & Counting Rooms
IRRAD Proton Beam Characteristics
Beam Dimensions• Several optic variants possible on T8• Standard size: 12x12 mm2 (FWHM)• Spot size from 5x5 to 20x20 mm2
Beam Intensity• p+ are delivered in “spills” of ~4×1011 p
• No. of spills/frequency depends on CPS
• Typical CPS duration: 30s
• Typical figures (high intensity): 3 spills per CPS• ~1 × 1016 p cm-2 5days-1 (12x12 mm2 FWHM)• about 4x more than the old facilities!
• Design figures (maximum): 6 spills per CPS• ~1 × 1017 p cm-2 4days-1 (5x5 mm2 FWHM)
Zone 1Zone 2
Zone 3 Zone 1
Cryogenic System
Shuttle System
Digitizes BPM detector signals in the 10pA to 500pA range
‒ dynamic range adjustableUses commercial off the shelf, low-
noise switched integrators to amplify the BPM signals
‒Texas Instruments ACF2101‒TI ADS1115
(16 bit, 2-3 bits noise)
On-line & Off-line Data Analysis and Alarms
Ongoing Upgrade
Mini-BPM device for precise alignment of irradiation equipment and or “big” samples Increased spatial resolution w.r.t. single-pad BPM
Up to 4 mini-BPM & 4 pads readout with one system
FRONT
BACK
The calculation of X0, Y0,σx and σy embedded inthe BPM display treatsthe data as discretevariables: not preciseenough for physics dataanalysis!
The new algorithm basedon Python libraries,reconstructs the 3D beamenvelope with ~2%precision for σx,y and ~4%precision for the centroid.
A Software BPM Alarm systemregularly checks the data flowand evaluates the beamconditions with the followingorder: Beam presence Beam intensity Beam stability Beam centre
The BPM Alarm system sendsnotification or alarms in casethe above parameters areoutside the specified limits.
