radmonmeeting july 2009 - university of...

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Michael ShupeUniversity of Arizona

Tucson, Arizona ATLAS Radiation Monitors

University of ArizonaMonitors MeetingJuly 21, 2009

Michael Shupe, Leif Shaver, Michael Starr,Matt Adams (2007-08, undergraduate)

University of Arizona

Michael Shupe, Leif Shaver, Michael Starr,Matt Adams (2007-08, undergraduate)

University of Arizona

Measuring Atlas Radiation Backgrounds in the Muon System at Startup:

A U.S. ATLAS Upgrade R&D Project

Measuring Atlas Radiation Backgrounds Measuring Atlas Radiation Backgrounds in the in the MuonMuon System at Startup:System at Startup:

A U.S. ATLAS Upgrade R&D ProjectA U.S. ATLAS Upgrade R&D Project

THIS WORK IS AN ATLAS UPGRADE R&D PROJECT, FUNDED THROUGH THIS WORK IS AN ATLAS UPGRADE R&D PROJECT, FUNDED THROUGH U.S. ATLAS.U.S. ATLAS.

PEOPLE: PEOPLE: Currently, M. Shupe. Later, A. Currently, M. Shupe. Later, A. SavineSavine. We are about to . We are about to recruit a recruit a postdocpostdoc who would work partwho would work part--time on this project.time on this project.

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1

Inner bore of Forward Toroid is a critical thin spot in the current design. May need redesign to reduce background rates after LHC Upgrade.

Beam pipe is a large background source. May need to be changed to beryllium.

LHC Upgrade Issues in the LHC Upgrade Issues in the MuonMuon SystemSystem

MuonMuon region region safety factors safety factors are 2are 2--5!5!

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Aims/Scope of This ProjectAims/Scope of This Project

•• Measure neutron, photon, and charged particle fluxes Measure neutron, photon, and charged particle fluxes and spectra in pulsed mode for sensitivity at low and spectra in pulsed mode for sensitivity at low luminosity. Compare measured fluxes to luminosity. Compare measured fluxes to FlukaFluka, , GCalorGCalor, , Geant4, etc., then Geant4, etc., then ““retuneretune”” simulations.simulations.

Reduce Reduce muonmuon safety factors, for realistic R&D.safety factors, for realistic R&D.•• Monitor sets are at the following CMonitor sets are at the following C--End locations: End locations:

(1)(1) In CSC region, at small r in Small WheelIn CSC region, at small r in Small Wheel(2) (2) In TGC1, at small r in Big WheelIn TGC1, at small r in Big Wheel(3) (3) In TGC2, at slightly larger r In TGC2, at slightly larger r (4)(4) On UX15 On UX15 endwallendwall, just outside TAS shield , just outside TAS shield (5) (5) On UX15 sidewall, opposite USA15 On UX15 sidewall, opposite USA15

•• All backgrounds are mixed particle types, and broad All backgrounds are mixed particle types, and broad spectrum.spectrum.

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1

TGC2TGC1

CSC

Side Wall to USA15

End Wall

Monitor Set Locations

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Monitor Set, Installed in TGC2 Wheel, July, 2006.Monitor Set, Installed in TGC2 Wheel, July, 2006.

4

3

21

Six scintillation detectors and one boron-lined proportional tube

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Monitor TypesMonitor Types

Gas detectors (sealed):proportional tubes with doped gases or linings.

Scintillators: crystals, plastic wafers, or liquid cells: 1” x 1”, coupled to PMT’s. Some are doped with boron or lithium for thermal neutron detection.

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Thermal Neutron DetectorsThermal Neutron Detectors(1) Boron lined proportional tube: n + 10B —› 7Li + α

Li or α ionize heavily. Pulse-height discrimination minimizes γ and MIP backgrounds.

Or, Proportional tube with BF3 gas: not as radiationresistant as (1), but cleaner signal separation.

(2) Boron doped plastic scintillator, on PMT:Same reaction. Run beside undoped counter of sameconstruction. Find n flux by subtraction.

(3) ZnS(Ag) plastic scint with 6Li: Old favorite.

Efficiencies are well defined, and Efficiencies are well defined, and rates are easy to extract online.rates are easy to extract online.

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Photon SpectroscopyPhoton Spectroscopy

(1) LSO Crystal: St. Gobain PreLude 420 (LuYSiO:Ce) crystal: high density (like BGO), thermal stability (unlike BGO).

(2) NaI(Tl) Crystal: Will damage sooner, but well understood.

Atlas test beam background fluxes were measured using a BGO Atlas test beam background fluxes were measured using a BGO crystal outside iron shielding, and were reported in 2000 by Chrcrystal outside iron shielding, and were reported in 2000 by Chris is FabjanFabjan, , EddaEdda GschwendtnerGschwendtner, and Helmut , and Helmut VinckeVincke. They demonstrated . They demonstrated that mixed neutron and photon fluxes could be analyzed by convolthat mixed neutron and photon fluxes could be analyzed by convolving ving simulated spectra with the scintillation detector response. Oursimulated spectra with the scintillation detector response. Ourscintillatorscintillator choices: choices:

Some spectral features can be picked out and reported online. BSome spectral features can be picked out and reported online. But ut full understanding of spectra requires offline analysis by full understanding of spectra requires offline analysis by simulation and convolutionsimulation and convolution——as with earlier BGO work.as with earlier BGO work.

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Fast Neutron DetectorsFast Neutron Detectors

(1) Liquid Scintillator Cell, NE213:PMT pulse-shape discrimination (PSD), is used to separate recoil proton pulses (large slow component)from photon and MIP pulses. PSD requires fastwaveform recorders, and is becoming more commonpractice in the nuclear physics community.

(2) NaI(Tl):PSD can be applied to these standard scintillators as well, but the discrimination threshold is higher—above 10 MeV.

(3) ZnS(Ag) plastic scintillator (undoped): Sensitive to recoil protons.

Fast neutrons in hydrogenic materials scatter elastically, producing slow recoil protons. Threshold ~ 1 MeV.

As with photon spectra, this requires detailed offline analysis.As with photon spectra, this requires detailed offline analysis.

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Detector Calibration at ArizonaDetector Calibration at Arizona

LSO Spectrum•• All detectors calibrated with All detectors calibrated with Co60 and Cs137 gamma sources.Co60 and Cs137 gamma sources.

•• First monitor set also tested First monitor set also tested with with PuBePuBe and and CfCf neutron neutron sources at Nuclear Engineering.sources at Nuclear Engineering.

•• Spectra taken with cable Spectra taken with cable lengths up to 100 m, the lengths up to 100 m, the maximum needed for installation maximum needed for installation in ATLAS.in ATLAS.

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ATLAS Big Wheel at C End:

Radiation monitor sets, TGC1 and TGC2, are near beam in horizontal sectors, between TGC chambers, near the beam on the side nearest USA15.

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Small Wheel monitors installed on surface – Bldg. 190

Same positioning as in TGC1 USA15 side nearest beam.

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ATLAS DAQ: Local and Remote, Analysis and MonitoringATLAS DAQ: Local and Remote, Analysis and Monitoring

Monitor Set 1

e.g. NaI, ZnS, LSO, 10B prop

tube, ion chamber, etc.

MUX

64 inputSet 2 (8)

Set N (8)

Set 3 (8)

Cavern USA15

MCA

5ns,12bit,32Ms

DMX 2

outpt

64 Channel Discriminate

& Scale

DAQ PC

atlasgw

Gain and shaping for pulse height analysis are computer controllable.

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Fluxes in KHz/cmFluxes in KHz/cm22 at luminosity 10at luminosity 103434::

n,thermn,therm n,fastn,fast γγ<10MeV<10MeV γγ>10MeV>10MeV h>10MeVh>10MeV

CSC RegionCSC Region 40.6 38.1 31.8 0.74 7.340.6 38.1 31.8 0.74 7.3

TGC1 RegionTGC1 Region 3.2 1.7 15.8 .061 .593.2 1.7 15.8 .061 .59

TAS region TAS region 1.5 1.3 1.82 .023 .078 1.5 1.3 1.82 .023 .078

Fluxes, and Sensor Counting RatesFluxes, and Sensor Counting Rates

EGEG: : 1010B lined proportional tube with A = 70 cmB lined proportional tube with A = 70 cm22, , εε = .001, operating = .001, operating at a luminosity of 10at a luminosity of 103333, counting thermal neutrons, with pulse height , counting thermal neutrons, with pulse height discrimination against other backgrounds:discrimination against other backgrounds:

CSC: 284 Hz TGC1 : 22.4 Hz CSC: 284 Hz TGC1 : 22.4 Hz EndwallEndwall: 10: 10--20 Hz20 Hz

Looks reasonable. We are applying this analysis to all sensors.Looks reasonable. We are applying this analysis to all sensors.

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(1) (1) ““InstantaneousInstantaneous”” RatesRatesDoped detector raw rates above a threshold.Doped detector raw rates above a threshold.Can be converted to instantaneous flux and sent to ControlCan be converted to instantaneous flux and sent to Control Room.Room.

(2) (2) ““Fast TurnFast Turn--AroundAround”” RatesRatesSpectrum features that can be fit above a background, and Spectrum features that can be fit above a background, and

used to extract instantaneous flux.used to extract instantaneous flux.Can be sent to Control Room, less frequently than (1).Can be sent to Control Room, less frequently than (1).

(2) Offline Analysis(2) Offline AnalysisFull spectra are sent to Arizona, and elsewhere, for offliFull spectra are sent to Arizona, and elsewhere, for offline ne

analysis using simulation and convolution to separateanalysis using simulation and convolution to separate mixed mixed backgrounds.backgrounds.

These would be used, in turn, to reweight the simulations andThese would be used, in turn, to reweight the simulations andreduce the safety factors, making the upgrade simulatreduce the safety factors, making the upgrade simulationsionsmore precisemore precise. This is, in effect, a . This is, in effect, a ““test beam runtest beam run”” done done in in situ. situ. (MPX detectors also have this capability.)(MPX detectors also have this capability.)

Operating ModesOperating Modes

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StatusStatus

•• The AZ The AZ RadMonRadMon DAQ system is cycling through all DAQ system is cycling through all scintillation detectors taking spectra with various scintillation detectors taking spectra with various gains and running times. UX15 is one of the leastgains and running times. UX15 is one of the least--radioactive places on Earth at the moment, so theseradioactive places on Earth at the moment, so theseare exceptionally dull. Weare exceptionally dull. We’’ll see if there is any ll see if there is any identifiable activity coming from the special concreteidentifiable activity coming from the special concretebehind the wallbehind the wall--mounted detectors.mounted detectors.

•• The proportional tubes will be set up soon.The proportional tubes will be set up soon.

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Internet Access Mode?Internet Access Mode?The DAQ computer is connected to the P1 internet, andThe DAQ computer is connected to the P1 internet, andat present we are accessing it in at present we are accessing it in ““expertexpert”” mode to allowmode to allowfor remote software development and commissioning.for remote software development and commissioning.This status will be revoked as LHC operation nears. At This status will be revoked as LHC operation nears. At that point we will need a robotic interface (GUI or script)that point we will need a robotic interface (GUI or script)to to atlasgw.cern.chatlasgw.cern.ch that allows for specification of all that allows for specification of all run conditions, and controls the outflow of data to therun conditions, and controls the outflow of data to theC.R. and elsewhere.C.R. and elsewhere.

It would be preferable to continue to have remote accessIt would be preferable to continue to have remote accessto the DAQ computer. Is it possible to put it to the DAQ computer. Is it possible to put it onlyonly on the on the publicpublic internet in P1, and then have a robotic process internet in P1, and then have a robotic process running on running on lxpluslxplus to feed data to the C.R. through a muchto feed data to the C.R. through a muchsimplified simplified atlasgwatlasgw interface?interface?

radmonmeeting july 2009 - university of...

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