New & Old Calorimetry Technologies with New Tools for LC

Y.Onel, University of Iowa

D.R.Winn, Fairfield University

ALCPG - Victoria Linear Collider Workshop

July 28-31, 2004

(a) Secondary Emission Calorimeter Sensors(b) Cerenkov Compensated Precision Calorimetry(c) Quartz fiber Calorimetry

Energy-Flow & Digital Calorimeters

• Problem: Finding Compact & Robust Ionization Sensors to make calorimeter “pixels” inside a large device.

Proposed Solutions:

(a) Secondary Emission Modules

(b) New Ultra-Compact PMT

• SE Rad-Hard, Fast– Dynodes survive 100 Grad equiv.– SEM monitors normal beam diagnostics

• Signal from SE surface(s): – ~0.1-1 SE per mip/e >100 KeV– 1<SE<2,000 per e<100 KeV (dep. on surface)

• Gain:– 1<g<10,000 per module

• Metal sheet dynodes (6-8 stages)• Large area SiMCP• Thin B-doped Diamond:Cs SE film + W foil

Secondary Emission Ionization Sensor Modules

SE Modules

• CAN BE MADE COMPACT for Energy-Flow Digital Calorimeter Modules

• SE is very robust, long lined and will require no maintenance nor suffer degradation

(a) Secondary Emission Sensor Modules for Calorimeters

• Basic Idea:A Dynode Stack is an Efficient High Gain Radiation Sensor

- High Gain & Efficient (yield ~1 e/mip for CsSb coating)- Compact (micromachined metal<1mm thick/stage)- Rad-Hard (PMT dynodes>100 GRads)- Fast- Simple SEM monitors proven at accelerators - Rugged/Could be structural elements (see below)- Easily integrated compactly into large calorimeters

low dead areas or services needed.

SE Detector Modules Are Applicable to:- Energy-Flow Calorimeters- Polarimeters- Forward Calorimeters

Basic SEM Calorimeter Sensor Module Form

“A Flat PMT without a Photocathode as replaced by an SE Surface”:- The photocathode is replaced by an SEM film on Metal.- Stack of 5-10 metal sheet dynodes, or a Si MCP in a metal “window”-

ceramic wall vacuum package about 5-10 mm thick x 10-25 cm square, adjustable in shape/area to the transverse shower size.

- Sheet dynodes/SiMCP/insulators made with MEMS/micromachining techniques are newly available, in thicknesses as fine as ~0.1 mm/dynode

- Ceramic wall thickness can be ~2mm, moulded and fired from commonly available greenforms (Coors, etc.)

- Outer electrodes (SEM cathode, anode) can be thick metal, serving as absorber and structural elements.

Schematic of SEM Calorimeter Sensor Module

brazed ceramic insulators

10 mil HV insulator (polymer)

signal (male)

signal (female) -optional for stacking

film bias resistor chain

1.8 mm thick Cu

HV connector

HV female socket (optional for stacking)

stackable

-2kV

signal out6 dynodes (200 µm thick @ 0.8mm spacing) 50ž

2 silicon micro channel plates

Cs3Sb SEM Surface

1cm

15 cm

top view

ceramic

Cu plate

• Dynode stages ~100-200 m thick

• Self-Supporting, Self-Aligning

• No Separate Vacuum Envelope

• Standard MEMS, Fab Tooling, Economics

• Thickness 8 Stage “PMT”<3 mm w/ 0.5-30 cm diameter!

• Channelized Photocathode, p.e. gain, and Anode– Essentially No Cross-Talk

– > ACHTUNG! High B-field operation

New PMT

Micromachined Metal Cs3Sb Coated mesh-like but channelized microDynodes – available up to 30 cm diameter

View Down Single Channel of Stack,Showing Offset

Mesh Dynode(L)And AssembledStacks(R).Channel Width~200 m

SEM & Compact PMT Calorimeter Sensors

• Iowa/Fairfield Propose Constructing Prototype SEM sensor module with gain of 105, 8 cm x 8cm.

• Iowa/Fairfield Propose acquiring compact PMT and building 20 cm cube calorimeter module

b) Cerenkov Compensation Precision Calorimetry

• Basic Idea:Cerenkov Light is most sensitive to electrons (photons)

Ionization sensitive to neutrons, hadrons, electronsUse these 2 measurements to correct calorimeter energy – stochastic & constant terms

- Detect both Cerenkov Signal Ec and Ionization Ei on the same shower.- For pure e-m showers, normalize the detected energies so that Ei = Ec = Eem.- For hadrons, only when only 0 are produced does Eh ~ Ei ~ Ec. - As Eh fluctuates more into n, +-, etc., Ec decreases faster than Ei. - On an Ec vs Ei scatter plot, the fluctuation is correlated/described by a straight line with slope

a<1, from which the constant is defined by a = /(1+).- The Ec vs Ei correlation yields an estimate of the compensated E as:

Ecomps = Ei + (Ei-Ec),where the constant is different for each calorimeter material/design.For electrons, Ecomps = Ei = Ec, since (Ei-Ec) = 0

- No “suppression” needed for compensation, thus more active material can be used, up to 100%, thus reducing the stochastic term.

- Two independent measurements enable tuning the constant term to near zero.

Cerenkov Compensation MC Results

• GEANT MC Checked by reproducing data:- pions in Lscint (10% stochastic, 10% constant term, FNAL E1A)- pions in PbGlass (35% stochastic, 10% constant – Serpekov)- e in PbGlass (5% stochastic – Dubna)- e in Cu/Quartz fibers(1.5%) (80% stochastic, 1% constant – CMS)

• Infinite media (LAr, Lscint, BaF2, NaI(Tl)), counting detected ionization and Cerenkov light yields (filters for scintillators): E/E ~ [11%-16%] E-1/2, with constant terms <1%.

• Model Cu absorber Sampling Fiber Calorimeter15% 0.8 mm clear fibers, 35% 0.8 mm scintillating fibers:- E/E ~ 18-20% E-1/2, with a constant term <0.5%.

Potential Applications in LC

• Compensating E-M & Hadron Calorimeters- CMS experience: combined crystal em + compensated hadron Calorimeter: hadrons

E/E ~ 90-100%E-1/2 + 3-4% - unacceptable for LC performance.

- To correct a crystal em+hadron system, Add a 2nd wavelength filtered Cerenkov photodetector to each crystal to compensate the crystal e-m calorimeter. Combined em+hadron Resolution should reach resolution of compensated hadron alone.

- To correct any highly non-compensated em calorimeter, add some Cerenkov (or electron-sensitive) detector.

• High Precision Sampling Hadron Calorimeter- MC indicates that E/E ~ 20%E-1/2 + <1% practical

- Energy-Flow possible with Clear & Scintillating “bricks”

read-out with WLS fibers, similar to ATLAS, CMS schemes.

Future Work on Cerenkov Compensation

• Iowa/Fairfield are proposing to beam-test crystal compensation.

• More Detailed GEANT4 MC of possible fiber and energy-flow designs in progress.

(c) Quartz Calorimetry

• The detector is intrinsically radiation hard at the required level (hundreds of MRads)

• The detector, for all practical purposes, is sensitive to the electromagnetic shower components (M)

• It is based on Cherenkov radiation and is extremely fast (< 10 ns)

• Low but sufficient light yield (<1 pe/GeV)

• The effects of induced radioactivity and neutron flux to a great extend are eliminated from the signal

• Neutron production is considerably reduced (high-Z vs low-Z)

• The detector is relatively short

• The detector is perfectly hermetic

Cherenkov Light Generation

• When high energy charged particles traverses dielectric media, a coherent wavefront is emitted by the excited atoms at a fixed angle : called Cherenkov light.

• Light is generated by Cherenkov effect in quartz fibers

• Sensitive to relativistic charged particles (Compton electrons...)

• d2N/dxd=2 q2(sin2c / 2)

=(2 q2/ 2 )[1-1/2n2]

min = 1/n

Emin ~ 200 KeV

• Amount of collected light depends on the angle between the particle path and the fiber axis

Iowa-Fairfield-ORNL-Tennessee-Mississippi

PPP-I Schematic View

PPP-I

Fiber Bundles(EM, HAD and TC)300-micron core

QP

Ferrules

ROBox( Light Guides)

R6425 PMTs

Iron Absorbe

r(9.5 I)

Radioactive Source

Tubes

3 x 3 Tower structure

(6 cm x 6 cm)

LED, Laser and PIN

PDs

Previous Experimental Data on Photodetectors by HF Group

R6427

HF Pulse Shape

25 ns

Spatial Uniformity w/ e- beam

Spatial Uniformity w/ - beam

PPP-I Response to 100 GeV e- and 225 GeV -

Energy Response Linearity

HF PPP1 responds linearly within 1% to electrons in the energy range tested (6 – 200 GeV). The - response is highly nonlinear.

Energy Resolution

Energy resolution of a calorimeter is parameterized as (/E)2 = (a/E)2 + b2

a/E : sampling term : Characterizes the statistical fluctuations in signal generating processes. b : Constant term: Responsible for the imperfections of the calorimeter, signal collection non-uniformity, calibration errors and leakage from the calorimeter.

HF Wedge

First HF End Completed

First HF End Completed

Summary

• SE Modules Have Good Potential

• Cerenkov Compensation may enable precision jet calorimetry when combined with digital/energy-flow designs.

• Quartz fiber calorimetry with multi-anode PMT readout could be used in the LC forward region.