C.Woody BNL sPHENIX EMCAL Conceptual Design sPHENIX Design Study Meeting September 7, 2011

C.WoodyBNL

sPHENIX EMCAL Conceptual Design

sPHENIX Design Study Meeting September 7, 2011

C.Woody, sPHENIX Design Study, 9/7/11 2

Requirements for the EMCAL• Original Decadal Plan had coverage in the central region over 2 in azimuth and || < 1, plus 2 < < 4 in the forward direction (one side)

• Calorimeter needed to be hermetic and projective

• To handle shower overlaps in central Au+Au collisions required - Small Moliere radius (~ 2 cm) - High segmentation ( ~ .01, ~ .01)

• Occupancy was thought to be an issue for R=60, RM=2 cm (Anders calc)

• Energy resolution ~ 15%/E

The energy resolution requirements will determine the sampling fraction, which will in turn have an impact on RM, X0 and abs, which then determine the transverse segmentation and longitudinal depth

• Identifying single photons from 0s up to pT ~ 40 GeV/c requires a preshower detector with () ~ .0005 (~ 300 m at R = 60 cm)

• Would like to get sufficient e/ rejection to do J/ and Y physics

• At least part of the EMCAL would be inside the magnetic field


Decadal Plan


sPHENIX Strawman Revised

C.Woody, sPHENIX Design Study, 9/7/11 5M.Perdekamp. RHIC Users Meeting, June 2011


Can we reuse the existing PHENIX EMCAL in sPHENIX ?

• How would the present detector modules be reconfigured to cover the desired rapidity range ?

• Could any part of it be used in the forward direction ? (high rapidity density, short radiation length, radiation damage ? )

• Non projective, not hermetic

• Large Moliere radius (RM ~ 3-4 cm)

• Will the PMTs work in the high fringe field of the new open solenoid or other magnetic field configuration ?

• We would probably want new electronics and a new HV system if we were going to reuse it for another 10 years

• How would the presence of the PMTs, HV and readout electronics affect the HCAL behind it ?

• What would be the cost of reconfiguring part of the existing EMCAL versus mounting a new one ?


PHENIX Shashlik EMCAL

=0.01, = 0.01 5.5 x 5.5 cm2 towers at R = 5m (15,522 towers total)

Alternating stack of lead and scintillator platesWavelength shifting fibers pass longitudinally through the stackFibers are bundled in the back and read out with PMTs

%1.2%1.8

EE

E pst 200~Light Yield ~ 1.5 p.e./MeV

PMT

WLS

Pb (1.5 mm) Scint (4 mm) 66 layers (18 X0)

4 towers Module36 Modules Supermodule18 Supermodules Sector6 Sectors

RM~ 3 cm


PHENIX PbGl EMCAL

%8.0%9.5

~ EE

E pst 300

Light Yield ~ 0.5 p.e./MeV

TF1 lead glass (= 3.85 g/cm3, n=1.648)9216 blocks4x4x40 cm3 (14.4 X0) RM~ 4 cm

Dominated by photostatistics(no sampling fluctuations)

24 blocks Module192 Modules Sector2 Sectors


Occupancy Question Revisited

Anders back of the envelope calculation implied the occupancy went from 2% in our present EMCAL (RM = 3 cm @ 5 m)

to 66% in the new sPHENIX EMCAL (RM= 2 cm @ 60 cm)

Benji Lewis carried out a more detailed simulation with GEANT and found that this was not the case

RM ~ 90% containment

RM

RM


Can the EMCAL (alone?) provide sufficient e/ rejection ?

Have been holding regular meetings (organized by Anne Sickles with Tony Frawley and others ) to look at the e/ rejection requirements to do J/ and Y physics

A. Sickles


What e/ rejection is required ?

Jeff Klatsky (FSU) But what about J/ ‘s with higher pT ?


Possible Designs for the “New” EMCAL for sPHENIX ?

Requirements:• Compact (“small” Moliere radius and “short” radiation length)• Projective• Hermetic• Readout works in a magnetic field• Low cost

Options:

• Optical accordion • Projective shashlik• Scintillating fiber

Any design must include a (presumably) tungsten-silicon preshower which would sit inside the magnet


Hybrid Option for PHENIX Central Calorimetry

-em energy resolution: 20% at 1 GeV

-em depth: 20 X0 or more;

-had. Resolution – better 50% at 1 GeV

-had depth: ~4 Labs

Si-Sc hybrid option

-Active preshower ~4 X0

-2 mm W (or equivalent) plates in preshower

-Si readout in preshower

-Pb & Sc in both E-sampling segments

-Optical readout in sampling segments

s-c magnet

EMC energy sampler Hadronic energy

sampler

Preshower

E.Kistenev


Self supporting structure

Optical Readout AccordionE.Kistenev


Shashlik W-Sc EMCal Module

square cross-section“a” slightly decreases from 15.0 mm to 14.9 mm as || increases

“b” slightly decreases from 16.8 mm to 16.7 mm as || increases

aa

bb

Thickness of W = 1.5 mmThickness of Scintillator = 1.0 mmRadiation length X0 = 5.8 mmuse 46 layers of W+ScDepth of the module = 20X0

Sampling fraction = 0.0569(rapidity independent)Position resolution = 2.8 mm at E = 1 GeV

= 0.9 mm at E = 10 GeV

Moliere Radius RM = 14.6 mm || x || segmentation = 0.0146 x 0.0146(Projective)~50 K ChannelsDon’t Need Preshower/SMD ?Energy resolution = 11.3 % / sqrt(E)Occupancy: 20 % (same assumptions for Pb)Price Quote: $8.2 M Total weight: 17.6 ton

J.Franz


Sci-Fi Design StudyA.Denisov and V.Bumazhnov (IHEP Protvino)

Two types of Scintillator+absorber structures have been simulated: 1) “spaghetti” with maximal geometrical sampling uniformity (left figure); 2)”slice” type for simplest mechanical treatment (right figure);

Simulations have been performed for calorimeter modules with cross-section of 300mm x 300mm and length of absorber of 200 mm(along of electron beam). The volume scintillator/absorber ratio is of about 30% for both cases. Geometry modification to take into account projective geometry requirements has not been implemented in this simulation yet. We believe that this effect should be small enough.

W and Pb absorbers


Summary

1. There are many open questions as to whether or how the present PHENIX EMCAL could be reused in sPHENIX

2. Occupancy in a new Compact EMCAL as proposed in the original Decadal Plan looks manageable

3. It appears that the calorimeter alone will not provide sufficient e/p rejection for J/ physics (although more studies are needed to settle this)

4. Several possible Compact EMCAL designs are being pursued that can hopefully deliver the performance required


Present - Andrei Sukhanov, Sean Stoll, Benji Lewis, Takao Sakaguchi, Anne Sickles, Rich Seto, Dimitri Kotchetkov, Chris Pinkenburg, Craig Woody, Bob Azmoun

Questions and issues to be addressed over the next 1-6 months:

1) What is the radius of the magnet ? Will there be some other field configuration in the forward direction ? This will drive the mechanical design of the EMC and HCAL

2) What resolution and segmentation do we really need for the EMCAL ? Physics input and supporting plots (Anne); detector design (Craig)

3) What should be the optimum thickness and segmentation of the Preshower (Rich)

4) What resolution is really required for the HCAL ? What is the driver? (heavy ions, pp, eRHIC) (Matthias Brian, Rich)

5) If we go to higher field, is there a dispersion between the neutral and charged components of the shower that could affect our jet measurement ? (Brian)

6) Need to include areas for support, infrastructure and service in the current design. Is integration cost included in the $20M ? (Ed) Need to include realistic cost estimates in all proposed designs (may exclude some options)

Summary of Calorimeter Working Group Discussions9/8/11


7) Need more contact and discussion with other groups who have recently built or are planning to build large calorimeters (CMS, ATLAS, JLAB, ILC…). New collaborators ?

8) Monte Carlo Studies (Chris) Study the effect of dead material on energy resolution, uniformity, etc.

A) Preshower+EMCAL inside magnet, HCAL outside magnet B) Preshower inside magnet, EMCAL outside ,then support stucture for HCAL, then HCAL C) Can we use the magnet coil as the first part (~ 1 Xo) of the Preshower ?

9) Need to develop a simple simulation for the accordion design (Edward ?)

10) How do we make a projective, hermetic, longitudially segmented calorimeter (Craig, Dmitri )

11) Given the recent results on e/pi separation (implying we need some other detector to identify electrons), can we give up longitudinal segmentation of the EMCAL, and if so, how would it affect jet measurements ? (Anne, Craig, Marzia, Tony, Jeff K.)

12) Could we do muon physics on the north side with an HCAL plus additional tracking and leaving the Mu-ID ? (i.e., can we flip our forward detector to the north side, leaving the south side free to built a electron spectrometer for e-RHIC ?


Backup Slides


FOCal 2011

2 mm W plates, ~5 X0 4 mm W plates, ~16 X0

22 layer of ~500 Si pads 15x15 mm2

8 layers of ~300 0.5 mm wide Si strips (4 X + 4 Y)

Segment - 0 Segment - 1 Segment - 2

-enhanced early shower measurements;

-reduced readout gaps to reduce shower

blow-up;

-resolved dynamic range problem.

E.Kistenev

0

Preshower separation

Provides good compactness due to thin sampling layers of silicon


Technology Choices

Material (g/cm3) RM (cm) X0 (cm) I (cm)

c (MeV)Sampling

W 19.25 0.93 0.35 9.6 8.0Pb 11.34 1.60 0.56 17.0 7.4Fe 7.87 1.69 1.76 16.8 22.0Si 2.33 4.80 9.36 45.5 41.0

Scint 1.05 9.60 42.40 79.5 94.0

HomogenousPbWO4 8.30 2.00 0.89 20.7

LSO 7.40 2.07 1.14 20.9PbF2 7.77 2.22 0.93 21.0

• Sampling vs Homogeneous

• Optical vs Ionization- Optical Scintillator (crystal, plastic), Wavelength Shifter, Cherenkov- Ionization Silicon, Noble Liquids (Ar, Kr, Xe)

• Readout Devices

“Apparent” RM ~ 1.8 cm due to Cherenkov

Reduced by sampling fraction


Pb-Sci-WLS Accordion (E. Kistenev and colleagues from IHEP circa ~2005)

Documents

C.Woody BNL sPHENIX EMCAL Conceptual Design sPHENIX Design Study Meeting September 7, 2011