# Presentation: 164747

## Mice Detectors

**Bross**
**NuFact 03**
**WG3**

## The MICE apparatus

**NB:**** Particle identification crucial ****– to avoid bias in ******** require non-muon contamination in final sample must be *****at most***** 1‰**

## Upstream Particle ID

**Beam is NOT pure**
**p, e, ******
**p,e easy to reject**
******’****s require some work**
**Decay in flight**
**	******** ******** ******** **
**Need to reduce to <.1%**
**TOF w/ 10 m ********L & 70 ps**
**Gives ******** sep better than 1%**
**OK if beam contamination is < 10%**
**Conventional scintillator/PMT technology**
**Just need to be careful**
**Well within current S.O.T.A.**
**Will add small beam Cerenkov for redundancy****	**
**C****6****F****14**** ****(n=1.25)**
**30 cm pathlength**

## Downstream PID

**Downstream PID**

**Must reject ******** ******** ****e decay in flight to <0.1%**
**Electromagnetic CAL + Aerogel Cerenkov**
**Cal**
**Scint (Fiber) + Pb**
**Signal in CAL consistent with ******** (MIP) AND no electron in Cerenkov**
**Some issues with fringe fields and size of CAL and shielding Cerenkov PMTs**

## Trackers

**The Real Problem**

## The Real-Real Problem: Backgrounds

**measured dark currents **

**real background **
**reduced by factor**
**L/X****0****(H****2****) . L/X****0****(det)**
**0.07          0.0026**

**The Real-Real Problem: Backgrounds**

**Dark current backgrounds measured **
**on a 805 MHz cavity in magnetic field**
**with a 1mm scintillating fiber at d=O(1m)**** **

**Extrapolation to MICE (201 MHz):**
**scale rates as (area.energy)   X 100**
**and apply above reduction factor 2 10****-4**
**4 10****4 ****Hz/cm****2 ****@ 8 MV/m @805 MHz**
**0.8 kHz/cm****2 ****per sci-fi  **
** ****500 kHz/plane/100 Hz/fiber**
**Another X5 reduction w/ timing**
** ****! within ******** one order of magnitude !**

**NOTE: EM Backgrounds can be problem for**
**Sensitive front-end electronics!**

## Scintillating-fiber tracker

**Scintillating-fiber tracker**

_**MICE SciFi group:**_
**UK groups**** ****with Fermilab, IIT, KEK and Osaka**

**350 ********m Fiber!**

## Status: mechanical design

**#1 ‘services ring’**

**Fibre station****:**

**Detail of design of optical connector**

## Visual light photon counters

_**VLPC Operational Principles**_
**Photon is converted in the intrinsic region, creating an electron-hole pair.**
**Hole drifts into the drift region, where it knocks an electron out from an atom.**
**Electron accelerates back through gain region, knocking electrons from atoms as it goes.**
**Spacer region and substrate are for mechanical support and field shaping.**
**Thus each photon generates a pulse of many electrons.  Gains of ×20,000 – 60,000 are achievable**

**Operated at 9K**

## VLPC performance

**VLPC performance**

**High QE**** ********80% **
**Low noise ****< 5X10****4 ****Hz (1 p.e.)**

**High Rate capability****: ****>40 MHz**
**High production yield: ********70%**

**No light**

**Light**

## Scintillating-fiber tracker performance

**concept**

** ****Sci-Fi studies **
**  ****with **
**G4MICE**

**background**** simulated ****1000 times larger**
**that extrapolated****  from measurements **
**does NOT degrade**** resolution seriously**
**(No multiplexing here!)**
**further improvements from the RF cavity**
**will be seeked (TiN coating) etc...**
**looks good****. **
**if this is confirmed, one ****could**** envisage **
**run****ning with ****higher gradients****. **
**This is possible if **
**-- 8 MW power to one 4-cavity unit**
**-- LN****2**** operation **

**in**

**out**

**Scintillating-fiber tracker performance**

## Scintillating-fiber tracker performance

## Background tolerance of SciFi tracker

**Performance OK**

**Background tolerance of SciFi tracker**

## Multiplex Sci-Fi -- Reduce channel count (1/7) 

**Multiplex**** ****Sci-Fi**** -- Reduce channel count (1/7) **
**Seven 350 ********m fibres multiplexed ****by a 7:1 multiplexing wave guide**** ****into one VLPC pixel. **
**only be about a 10% loss of light in the outer ring of fibres due to a slight mismatch.**** **
**Pro: ****cheaper**** by factor 4 .... save 3 M !!!!!**
**Con: ****less sure**** to work in presence of bkgd and of a few dead channels. **

**OK i****f backgrounds from the RF cavities ****stays ****at a low level**** **

## Combining neighboring channels

**7 scint. fibres to 1 readout fibre: reduce channel count (cost)**

***p*****T**** resolution**

******(*****p*****T****)**
**Baseline: 0.17 MeV/c**
**7-to-1 mux: 0.27 MeV/c**

## TPG

**TPG**

**TPC with GEM readout**
**1 m long, 30 cm diameter**
**u,v,t projections like SciFi**
**90% He**
**Pro****	**
**100 points/track**
**Only ******** ****2X10****-4 ****X****o**
**Excellent pattern recognition**
**Con**
**Long (50 ********s) integration time**
**GEM sensitivity to x-rays?**
**Front-end electronics sensitivity to EM radiation?**
**Shielding**

## Gas Electron Multiplier (GEM)

- A thin polymer foil, metal-coated on both sides, is chemically pierced by a high density of holes. On application of a voltage gradient, electrons released on the top side drift into the hole, multiply in avalanche and transfer the other side. Proportional gains above 103 are obtained in most common gases.

## TPG

**at noise rate similar to that **
**simulated for fibers, **
**no difficulty finding tracks and measuring them.**
**resolution somewhat better than sci-fi (which is good enough)  **

**difficulty: nobody knows the effect of RF photons on the GEM themselves**
**tests in 2003, decision October 2003**

**TPG**

## Questions

**Can the tracker survive the backgrounds?**
**What are the backgrounds?**
**Test of 201 MHz cavity prototype**
**What effect does RF noise have on the tracking system?**
**How do tracking devices with conductors behave near RF cavities?**
**What effect do electrons from RF have on the tracking system?**
**What is the multiple scattering introduced by the tracking system for 200 MeV/c muons?  Whatever RF shielding the tracking system needs should be included.**
**What is the momentum resolution?**
**Has the system been shown to work either in an experiment or as a proto-type?**
**What is the estimated cost of the system?**
**How hard is it to run the detector and is manpower available to to maintain its performance?**