fpi for the cta project razmick mirzoyan for the fpi wp j. bolmont, p. espigat, d. fink, d. gascon,...

FPI for the FPI for the CTA projectCTA project

Razmick Mirzoyan for the FPI WPRazmick Mirzoyan for the FPI WP

J. Bolmont, P. Espigat, D. Fink, D. Gascon, G. Hermann, B. J. Bolmont, P. Espigat, D. Fink, D. Gascon, G. Hermann, B. Khelifi, E. Lorenz, P. Manigot, M. Punch, M. Shayduk, T. Khelifi, E. Lorenz, P. Manigot, M. Punch, M. Shayduk, T.

Schweizer, H. Sol, K.-H. Sulanke, P. Tavernet, M. Teshima, P. Schweizer, H. Sol, K.-H. Sulanke, P. Tavernet, M. Teshima, P. Vincent, H. Wetteskind, V. Zimmer, et al.,Vincent, H. Wetteskind, V. Zimmer, et al.,

13th of May 200913th of May 2009 R. Mirzoyan, et al., FPI for CTA; GenerR. Mirzoyan, et al., FPI for CTA; General Meeting, Cracow, Polandal Meeting, Cracow, Poland

Camera MechanicsCamera MechanicsH.E.S.S.-II camera under construction in Paris


Camera Mechanics: Cost EstimateCamera Mechanics: Cost EstimateExample: MAGIC-2, 1039-pixel camera Example: MAGIC-2, 1039-pixel camera


Camera SealingCamera Sealing

Namibia Tenerife

Arizona Australia


Camera SealingCamera Sealing

One needs to reduce the back-reflection from the surface(apply anti-reflective coating)


Cooling – temperature stabilisationCooling – temperature stabilisation

• It makes sense to split the imaging camera design into 2 parts:

1. T° sensitive sealed part(PMT, ampl., FADC,…) and

2. not sensitive to T° „open“ part(power supplies, e.t.c….)

• To cool and stabilize the T° only inside the sensitive part


Cooling – temperature stabilisationCooling – temperature stabilisation • An interesting idea is toconsider a distributedsystem of cooling for a cluster of nearby telescopes. Say every 4 telescopes share 1 system

• This may reduce the cost for the cooling system


Pop-up reflective target for miror Pop-up reflective target for miror reflectivity and pointing calibrationreflectivity and pointing calibration


Light Guide System: Experience of Light Guide System: Experience of H.E.S.S.H.E.S.S.


MAGIC: Optimization hex input – MAGIC: Optimization hex input – hex outputhex output

Exit Exit rad.rad.[mm][mm]

Photo Photo eff. [%] eff. [%]

NoiseNoiseeff. [%]eff. [%]

oldold 91.491.4 21.821.8

1111 92.292.2 16.916.9

10.510.5 91.591.5 13.413.4

1010 90.890.8 10.310.3

9.59.5 89.989.9 7.77.7

Masaaki Hayashida


Light Guide System: Experience of Light Guide System: Experience of MAGICMAGIC


Where the differences between H.E.S.S. & MAGIC Where the differences between H.E.S.S. & MAGIC Light Guide efficiencies are coming from ?Light Guide efficiencies are coming from ?

One possible explanation: One possible explanation: – H.E.S.S. is using flat window PMTs that H.E.S.S. is using flat window PMTs that

are touching the edge of the LG. are touching the edge of the LG. Incident light hits the PMT input window Incident light hits the PMT input window under very large angles, light under very large angles, light polarisation plays a big role polarisation plays a big role

– MAGIC is using hemi-spherical window MAGIC is using hemi-spherical window PMTs that „enter“ into the LG. Light hits PMTs that „enter“ into the LG. Light hits the photo cathode mostly under the photo cathode mostly under relatively small angles, providing higher relatively small angles, providing higher efficiency (also, double hits; the photo efficiency (also, double hits; the photo cathode is semi-transparent)cathode is semi-transparent)

The above needs to be checked The above needs to be checked soon: affects the selection of PMTsoon: affects the selection of PMT


HV system: Cockroft-Walton ?HV system: Cockroft-Walton ?Typical power consumption of a „classical“ resistive type voltage divider circuit (active or passive) is ~500 mW.1000 PMTs dividers willdissipate 500 W heat Cockroft-Walton typeconsumes ~ 15 mW1000 PMTs will dissipate15 W heat

Ideal solution could be: feed with 1 Cockroft-Walton a cluster of 10-20 PMTs

Need additional stabilisation of the photo-cathode to 1stdynode voltage @ ~300 V


Low Noise Power SuppliesLow Noise Power Supplies


BandwidthBandwidth

The bandwidth of MAGIC-I (from PMT to FADC, all The bandwidth of MAGIC-I (from PMT to FADC, all included) is about 230 MHz. We are really profiting from included) is about 230 MHz. We are really profiting from the parabolic shape and the ultra-fast readout of this the parabolic shape and the ultra-fast readout of this telescopetelescope– Reduced 2-3 times hadron backgroundReduced 2-3 times hadron background– Much lower pile-up of LONS photons, almost get rid of itMuch lower pile-up of LONS photons, almost get rid of it– Analysis at lower thresholds possible (sum-trigger, pulsar studies)Analysis at lower thresholds possible (sum-trigger, pulsar studies)

H.E.S.S. 28m telescope shall have a comparable ultra-fast H.E.S.S. 28m telescope shall have a comparable ultra-fast design.design.We believe that the entire signal chain for the large We believe that the entire signal chain for the large telescopes shall provide ≥ 200 MHz bandwidth. telescopes shall provide ≥ 200 MHz bandwidth. The mid-size telescopes known to work well with ≤ 80-100 The mid-size telescopes known to work well with ≤ 80-100 MHz bandwidthsMHz bandwidths


AmplifierAmplifier


Dynamic RangeDynamic RangeIn order to see a single ph.e. event from a PMT in a given bandwidth In order to see a single ph.e. event from a PMT in a given bandwidth its amplitude shall be ≥ 6 x amplifierits amplitude shall be ≥ 6 x amplifiernoisenoise

For a good fast amplifier the 1For a good fast amplifier the 1noise noise ~ 4000 ph.e. (equivalent)~ 4000 ph.e. (equivalent)

For CTA we aim for x10 higher PMT gain ≥ 40000 (10xFor CTA we aim for x10 higher PMT gain ≥ 40000 (10xnoisenoise))

A ~1´ PMT can deliver a linear dynamic range of ~ 5000 ph.e.A ~1´ PMT can deliver a linear dynamic range of ~ 5000 ph.e. in the ideal case, by assuming 1ADC count = 1/6 ph.e. (1ADC in the ideal case, by assuming 1ADC count = 1/6 ph.e. (1ADC count = 1count = 1noisenoise of the amplifier), one could cover a dynamic range of of the amplifier), one could cover a dynamic range of 6 x 5000 = 30000 (89.5 db) (15-bits = 32768)6 x 5000 = 30000 (89.5 db) (15-bits = 32768)Usually the precision of single ph.e. calibration is believed to be Usually the precision of single ph.e. calibration is believed to be ~10 %. Let us assume 1ADC count = 1/10 ph.e. ~10 %. Let us assume 1ADC count = 1/10 ph.e. obtain a dynamic obtain a dynamic range even higher: 10 x 5000 = 50000 (94 db) (16-bits = 65536)range even higher: 10 x 5000 = 50000 (94 db) (16-bits = 65536)A single ampifier could cover a dynamic range of ~3V/150µV = A single ampifier could cover a dynamic range of ~3V/150µV = 20000 (86 db) (probably this is already good enough although again 20000 (86 db) (probably this is already good enough although again a 15 bit digitalisation necessary)a 15 bit digitalisation necessary)


The above written is true when using a charge integrating ADC The above written is true when using a charge integrating ADC system. When using a fast FADC that produces sevaral samples for system. When using a fast FADC that produces sevaral samples for the minimum signal width of the PMT, the situation is somewhat the minimum signal width of the PMT, the situation is somewhat better, effectively one may „recover“ ~1 bit.better, effectively one may „recover“ ~1 bit.Alternative: if we abandon the option to measure the single ph.e. Alternative: if we abandon the option to measure the single ph.e. distributions from PMTs directly and assume that we could perform distributions from PMTs directly and assume that we could perform some alternative types of (ADC count/ph.e.) calibrations then one some alternative types of (ADC count/ph.e.) calibrations then one can set 1ph.e. = 1 ADC count and one needs to cover a dynamic can set 1ph.e. = 1 ADC count and one needs to cover a dynamic range of only 5000 (74 db) (13 bits = 8192).range of only 5000 (74 db) (13 bits = 8192).A FADC system shall provide either A FADC system shall provide either – a) a very wide dynamic range or a) a very wide dynamic range or – b) double readout system for any given channel or b) double readout system for any given channel or – c) have some smart design feature allowing one to expand its dynamic c) have some smart design feature allowing one to expand its dynamic

range (active or passive multiplexing) to a larger bit number. range (active or passive multiplexing) to a larger bit number.

We shall see how close can we come to the idealWe shall see how close can we come to the ideal

Dynamic RangeDynamic Range


Example: pixel & cluster designsExample: pixel & cluster designs

H.E.S.S.-IIPMT cluster

M-II cluster

M-II cluster


SiPM: recent newsSiPM: recent news

Sometime during this year at least 2 new manufacturers will start producing SiPMswith UV sensitivity. We are evaluating the newest products that can find application in CTA

H. MiyamotoTIPP-09


Full-automatic QE measuring Full-automatic QE measuring device @ MPI for Physicsdevice @ MPI for Physics


Photonis XP-52Y2 & XP-3060Photonis XP-52Y2 & XP-3060

Candidate PMTs from Photonis


Photonis XP-29600Photonis XP-29600


Photonis XP-3102/FL & XP-31SF Photonis XP-3102/FL & XP-31SF (hemi-spherical window)(hemi-spherical window)


1´ Hamamatsu against 1´ ET PMT, 1´ Hamamatsu against 1´ ET PMT, both hemisphericalboth hemispherical

ET PMT, coated with matt lacquer,Used in MAGIC-I

Hamamatsu Superbialkali, used in MAGIC-II

QE for the recent Hamamatsu QE for the recent Hamamatsu 1´ hemispherical PMTs for 1´ hemispherical PMTs for

the MAGIC-I upgrade camerathe MAGIC-I upgrade camera


QE for 3 candidate PMTs from QE for 3 candidate PMTs from Hamamatsu: 1´, 1.5´, 2´ sizesHamamatsu: 1´, 1.5´, 2´ sizes


1´ size Hamamatsu R86191´ size Hamamatsu R8619


2´ Hamamatsu R77242´ Hamamatsu R7724


1.5´ Hamamatsu R94201.5´ Hamamatsu R9420


AfterpulsingAfterpulsing


Electron Tubes EnterprisesElectron Tubes Enterprises


Conclusions-1Conclusions-1

PMT candidates for the CTA telescopes are preliminarily PMT candidates for the CTA telescopes are preliminarily selected from Hamamatsu (1.5´) and from ETE (1.5´ & selected from Hamamatsu (1.5´) and from ETE (1.5´ & 111/81/8´). The development work shall start very soon.´). The development work shall start very soon.Ideas about the camera mechanics are slowly Ideas about the camera mechanics are slowly crystallising.crystallising.A critical comparison of the PMT HV system is A critical comparison of the PMT HV system is underway. underway. Low-noise power supplies are targeted.Low-noise power supplies are targeted.Probably the advantage shall be given to an amplifier Probably the advantage shall be given to an amplifier that is integrated just behind the PMT. This may be very that is integrated just behind the PMT. This may be very useful in future when alternative light sensors may useful in future when alternative light sensors may become competitive with PMTs. This will make it become competitive with PMTs. This will make it relatively easy to upgrade with the new sensors the relatively easy to upgrade with the new sensors the imaging cameras of the CTA telescopes.imaging cameras of the CTA telescopes.


The necessary dynamic range is still under discussions The necessary dynamic range is still under discussions Low-noise, high bandwidth amplifiers are critically Low-noise, high bandwidth amplifiers are critically reviewed.reviewed.A critical comparison of the LG systems is underwayA critical comparison of the LG systems is underwayA camera of optimised sections is under study.A camera of optimised sections is under study.A camera sealing, cooling & T° stabilisation systems are A camera sealing, cooling & T° stabilisation systems are under study. Feasibility study of distributed system of T° under study. Feasibility study of distributed system of T° stabilisation system is under discussionstabilisation system is under discussionWe are discussing to have the next joint FPI/ELEC We are discussing to have the next joint FPI/ELEC meeting sometime in June or the beginning of July in meeting sometime in June or the beginning of July in some beautiful place in Bavariasome beautiful place in Bavaria

Conclusions-2Conclusions-2


Hamamatsu R9420 socketHamamatsu R9420 socket1,5-inch, active divider


HV system: Cockroft-Walton ?HV system: Cockroft-Walton ?


Masaaki Hayashida

MAGIC Light Guides: Possible MAGIC Light Guides: Possible loss of photonsloss of photons

Gap between the side wall (hex type has 6 walls)Gap between the side wall (hex type has 6 walls)– 0.3 mm (x6) -> 2 % of loss in total0.3 mm (x6) -> 2 % of loss in total

Gap between the cone and the photo cathodeGap between the cone and the photo cathode(ex. hex-hex, exit r = 10mm)(ex. hex-hex, exit r = 10mm)

Gap Gap [mm][mm]

11 22 33 44 55

Eff [%]Eff [%] 90.890.8 90.590.5 90.090.0 88.988.9 87.187.1


QE for the recent Hamamatsu 1-inch QE for the recent Hamamatsu 1-inch hemispherical PMTs for the MAGIC-I hemispherical PMTs for the MAGIC-I

upgrade cameraupgrade camera

fpi for the cta project razmick mirzoyan for the fpi wp j. bolmont, p. espigat, d. fink, d. gascon,...

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