Quartz Plate Calorimeter Prototype

Ugur AkgunThe University of Iowa

APS April 2006 MeetingDallas, Texas

Introduction• The calorimeters measure the energy of the neutral and

charged particles. The particles deposit their energy into the calorimeters through creation and absorption processes.

• The particles can interact primarily with: – Electromagnetic interaction– Hadronic (strong) interaction

• The deposited energy can be determined in a variety of ways:

– Ionization (Charge)– Excitation (Scintillation, Cerenkov)

• The dense medium may be active or passive:– Homogeneous calorimeters– Sampling calorimeters

Cerenkov Light Generation

When high energy charged particles traverse dielectric media, a coherent wave front, which is called Cerenkov light, is emitted by the excited atoms at a fixed angle .

The Cerenkov light is 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

Quartz Calorimetry

• The quartz detectors are intrinsically radiation hard.• The quartz detectors are sensitive to the electromagnetic

shower components.• The quartz calorimeter is based on Cerenkov radiation and

is extremely fast. It yields low but sufficient light.• All these make the Quartz

calorimeters a very good

option for the future

hadron colliders

Quartz Plate Calorimeter Prototype • We designed a quartz plate calorimeter prototype with 20 layers. • Each layer has 70 mm iron absorber and 5 mm quartz plates. • The cross section of the prototype is 20 cm x 20 cm. • The Cerenkov light is collected by wavelength shifting fibersand carried to the Hamamatsu R7525 PMT.

The Fiber Geometry• 1 mm diameter Bicron wavelength shifting fibers are uniformly distributed on quartz plates. They absorb photons down to 280 nm, and emit 435 nm.• The fibers go ~20 cm out of the quartz plate.

Calorimeter Response Linearity• For the sampling calorimeters the calorimeter response linearity is an important issue. Pathlength fluctuations and Landau fluctuations are the reasons of the detector nonlinearity.

• The Geant4 simulations of our prototype calorimeter shows that the detector response is linear up to 300 GeV.

Energy Resolution • The energy resolution of a calorimeter is defined as;

Where a - stocastic term, b - constant term and c- noise term

• The resolution of the prototype is simulated with different beam energies. It yields; a = 13.7 b = 0.16

Shower Profiles

-20

-5

107

42

77

112

01000200030004000

5000

6000

7000

8000

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10000

3D Shower Profile7

14

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49

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120 GeV Proton

• The hadronic showers are much broader and longer than the electromagnetic showers.• Our prototype is more than 8 interaction length long. λint for iron is 16.7 cm.

• The figure above shows the 3D simulation of the shower. Transverse shower profiles show some leakage, but it is not Cerenkov capable part of the shower. 10 cm radius contains ~100% of the Cerenkov core of the shower.

Transverse hadronic shower profile for different energies of proton beam

10

100

1000

0 50 100 150

Depth in Iron (cm)

Sig

na

l (a

.u)

66 GeV

120 GeV100GeV

80Gev

60GeV40GeV

20GeV10GeV

100

1000

10000

100000

-30 -20 -10 0 10 20 30

Beam Position (cm)

Res

po

nse

(a.

u.)

Longitudinal hadronic shower profile for different energies of proton beam

Fermilab Test Beam• We tested some layers of the prototype at the Fermilab Meson Test area with 120 GeV and 66 GeV positive beam. • All quartz plates with fibers are wrapped with Tyvek and black tape.• They are put into an aluminum frame which carries the PMTs, and wrapped again to make them light-tight.• All quartz plates and absorbers are supported by a rail system.

Geant4 Simulation

1000

10000

100000

0 50 100 150

Depth in Iron (cm)

Re

sp

on

se

(a

.u.)

66 GeV

120 GeV

Test Beam

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0 20 40 60 80

Depth in Iron (cm)

Re

sp

on

se

(a

.u.)

120GeV

66GeV

• Although we have only 6 layers, we got data at different absorberdepths (up to 70 cm of iron). • We developed our own data acquisition system with NIM, CAMAC and LabView. • With limited number of layers we observed a full shower profile at 120 GeV.• The 66 GeV has very low statistics.

Conclusion and Future Plans• The “Generation 1” Quartz Plate Calorimeter Prototype showed promising

preliminary simulation and test results.• Its portable design allows to test different configurations.• Since it is radiation hard, it can be used in the future collider experiments.• This summer we have one week beam time at CERN:

– We will take electron and pion beams at different energies. Experimental measurement of electromagnetic and hadronic energy resolution of the prototype.

• We will take beam at Fermilab M-Test area, in Fall 2006.• We plan to create a small ECAL unit in front of the prototype.

References:Nucl. Instr. and Meth. A399, 202, 1997Nucl. Instr. and Meth. A399, 202, 1997Nucl. Instr. and Meth. A408, 380, 1998Nucl. Instr. and Meth. A408, 380, 1998

J. Phys. G: Nucl. Part. Phys. 30 N33-N44, 2004J. Phys. G: Nucl. Part. Phys. 30 N33-N44, 2004 CMS NOTE 2006/044CMS NOTE 2006/044