Low Beta Muon Collider Detector

M. A. C. Cummings

MC Design Workshop

JLab, Dec. 11, 2008

The situation:

Last serious design effort was Snowmass 1996Lack of coverage in the forward/backward angular region:

Shielding is necessary against electrons from muon decays The area < 20 degrees for/back was inert material (tungsten), but possibility down to < 9 degrees considered Serious limitation to possible physicso Top production in forward regions as CoM energy goes upo Asymmetries are more pronounced in forward regionso Z’ => ttbaro Final states with many fermions (like ordinary SM tt-events)

are hardly ever contained in the central detectorAdvances in detector technologies have made extending the

forward reach possible – minimizing a competitive disadvantage with linear colliders

Physics advantage for MC

• In all other respects, the physics yield from muon colliders is the same for electron machines, with 2 important advantages from the muon’s large mass:

• More fundamentally, it will be the first machine to collider a different family of particles

Superior energy resolutionS-channel Higgs production

“Strawman” detector, Snowmass, 1996.

Illustration of a quadrant of a typical detector at a muon collider. The forward region, within a 20° cone, is filled with dense shielding, and is not instrumented. In this document it is proposed to investigate the feasibility of instrumenting this forward area for particle detection.

IP Region

Sketch of the IP region and 130 meters of the final focus magnet system with quadrupoles (Q) and toroids (T). This sketch shows the geometry of the detector used in the 1996 GEANT simulation of a 2 × 2 TeV Muon Collider. The conical tungsten-filled region, shown in dark blue, was required to absorb debris from muon decays in the beams. Because of the limitations of detector technology at the time, this area was not instrumented.

Muon Collider Parameters ReconsideredInstrumenting more of the small angle region of the detector, the number of muons/bunch becomes critical:The three scenarios is different by a factor of 20. These muons and their electron decay products are responsible for the largest component of background in the photon detectors to study.The physics consequences of machine design choices will be significant. OTOH: if we can show that modern sensors and electronics can handle very large numbers of decay products, machine designers will have more freedom.

Calorimetry

(E)/E ~ 3-4% is achievable

– e.g. ability to separate Z -> qq, W -> qq’

• 2 orders of magnitude better time resolution

• New Dual or triple readout

– Particle Flow Algorithm (PFA)

• Enabling technologies

– New generation of photon detectors

– Highly integrated microelectronics

• Strategies

– Digital vs. Analogue readout• Finer granularity

• Better ability to scale to large area detectors

Calorimetry Readout

Calorimetry Readout

Particle Flow Algorithm

Forward Calorimetry

Photon detectors• Developments in Geiger-mode avalanche photo diodes (SiPM, MPPCs,

e.g) have enabled great advances in calorimeter performance in challenging environments. – They are very compact and have high gain (~105) and good particle

detection efficiency. – Shown to be insensitive to magnetic fields as high as 4.4T – Have good (sub-nanosecond) time resolution.– Good radiation tolerance, with no deterioration seen at 1 Mrad gamma

radiation exposure. • The primary challenges are:

– Thermal noise rate. – Non-linear response (saturation effect), – Sensitivity to temperature change and cross-talk and after-pulsing.

• NIU SiPM: readout uniformity:

“dimpled”SiPM

NIU Calorimeter R & D: Calorimeter Tiles

(a): Examples of plastic scintillator tiles for use in calorimeters; (b): Array of scintillating tiles arranged on 1m x 1m plate of a prototype CALICE hadron calorimeter, built by the NIU group.

Candidate for “instrumented shielding” that will comprise a forward region muon collider detector, addressing the challenges of viability and particle ID requirements

a) b)

Major Issues for Phase I SBIR

• Scope of Muons, Inc. SBIR Phase I: establish the viability of

“instrumented shielding” to extend the physics coverage of a Muon Collider Detector by studying the

The limits of detector performance (e.g., cell occupancy, efficiency) in the forward interaction region as a function of muon collider bunch intensity and luminosity.

The shielding requirements for all detectors, especially those that might be affected by the instrumentation of the tungsten cone.

The optimization of the collider parameters and low beta insertion designs to minimize the beam-related backgrounds that get into the detector.

Muon Collider Detector Revision

• Prepare G4Beamline to simulate beam-induced backgrounds in sensor arrays of a large detector in the low-beta region of a muon collider.

• Verify the simulations by comparing distributions and rates to other codes, such as MARS, and to analytic calculations.

• Consolidate existing NIU and other photon sensor performance data and extend them as needed with new measurements.

• Compare the apparent requirements from the preliminary G4beamline simulations for at least one muon collider scenario with the performance data to identify inconsistencies or areas where improvement is needed in the devices, electronics, IP design, or machine parameters.

NIU Calorimeter R & D

Northern Illinois University (NIU) has been intimately involved with the design, optimization, construction, commissioning and operation of a silicon-tungsten electromagnetic calorimeter and a steel-scintillator hadron shower imager as part of the CALICE test beam program at the H6B area at CERN for a month each in 2006 and 2007. The hadron shower imager physically consists of two devices: a hadron calorimeter (HCAL) and a tail-catcher/muon tracker (TCMT). NIU had the primary responsibility for the latter device. The NIU group has pioneered use of arrays of plastic scintillator tiles in calorimeters. Samples of small tiles and an array of tiles mounted to a 1m x 1m plate in the CALICE hadron calorimeter are shown in Figure 5. As shown, the tiles are arranged as a mosaic with smaller tiles in the high rate regions and larger tiles farther away from the high rate areas. Earlier versions, as in Figure 5(a), were read out by means of fibers, but with solid state detectors such as MPPCs and integrated electronics, more compact highly efficient calorimeters are now being used. Using simulations to provide expected particle flux rates at different depths in the shielding cones, the sizes and arrangements of tiles that can function will be computed. Prototypes of “instrumented shielding” that will comprise a forward region muon collider detector will be designed.