# Presentation: 087307

## Statusof

**Is the CKM matrix the only**
**source of CP violation?**

**Leo Bellantoni**
***Fermilab Users' Meeting***
*June 2002*

## K+  

- (Buchalla & Buras, Falk *et. al.,*
-  D'Ambrosio and Isidori)

***Hadronic effects well understood***

**K****+**** ******** **************

## K+  

- 0.79  0.10

- <0.032

- (BNL)

- From fit by D'Ambrosio and Isidore, PL B530 (2002) 108 using above constraints, |Vub / Vcb|, K, and m(Bd)

## K+  

- The CKM result in the event of no new physics

## K+  

- In SUSY, branching ratio could be up to 210% (conceivably, much more) of the Standard Model value, leading to the above CKM result
-       Buras,Colangelo,Isidori,Romanino,Silvestrini
-                                       Nucl.Phys B566(2000)3.

## K+  

**K****+**** ******** **************

- In MSSM, branching ratio could be between 65 to 102% the Standard Model value, leading to the above CKM result
-              Buras,Gambino,Gorban,Jager,Silvestrini
-                                     Nucl.Phys B592(2001)55.

## K+  

- Buras et.al. found an "unlikely" SUSY scenario that gives enhancements of
*Br*(*K**+*  ) up to 3x the SM level
- Baek,Jang,Ko,Park, Nucl.Phys.,    B609(2001)442 also show a SUSY scenario where *Br*(*K**+*  ) differs markedly
- from the SM level
- Hattori,Hasuike,Wakaizumi, Nucl.Phys.,    B592(2001)55 also found large branching ratio enhancements in their 4 generation model
- D'Ambrosio and Isidori, Phys.Lett.,    B530(2002)108 discusses the case where
- new physics has led us to draw the wrong
- constraint from Bd mixing

## BNL E787 reports 2 clean events

With recent (, values, expect

BNL E949 (upgrade of E787) expects to see 5 - 10 events using stopped K+
Run has started
Needs 2 more years worth of data
Joint collaboration with CKM
     (FNAL / BNL / IHEP)

CKM plans to see 100 events using the Main Injector and decay in flight

- With recent (, values, expect
- BNL E949 (upgrade of E787) expects to see 5 - 10 events using stopped K+
- Run has started
- Needs 2 more years worth of data
- Joint collaboration with CKM
-      (FNAL / BNL / IHEP)
- CKM plans to see 100 events using the Main Injector and decay in flight

- PRL 88, 041803 (2002)

**K****+**** ******** **************

*at **** **3**** level,*

## Other Physics

- Lepton flavor violation
- K+  ++*e*-	K+  +-*e*+
- K+  -+*e*+	K+  -++
- K+  -*e*+*e*+
- T violation in K+  0l+
- Search for pseudoscaler in
-  K+  *e*+
- Direct CP violation in 3, 
- Form factors in K+  +l+l-

## Slide 10

## Detection

- Fiducial region limited by beam energy,
- background from K, use of RICH to
- measure + velocity, need for K++ vertex

- M2MISS = M2K(1 - p/pK) + m2(1 - pK/p) – ppK2

**100 events @ 17% x 1.6% x (8 x 10****-11****)**
****** ****Need ~4 x 10****14**** K****+**** !**

## RF separated K+ beam

***RF separated K******+****** beam***

## Turtle/GEANT simulation:
Debunched 22GeV beam  (+2%)
33MHz of K+ per 4 x 1012 ppp
71% Kaon purity
Total charged particle rate into detector <50MHz; muon component is 7.4MHz
Achieves baseline CKM requirements

- Debunched 22GeV beam  (_+_2%)
- 33MHz of K+ per 4 x 1012 ppp
- 71% Kaon purity
- Total charged particle rate into detector <50MHz; muon component is 7.4MHz
- Achieves baseline CKM requirements

- Need 5MeV/m P**** kick for 1sec spill **** need superconducting cavities to create the deflection

***RF separated K******+****** beam***

## RF separated K+ beam

***RF separated K******+****** beam***

## RF separated K+ beam

- 	This result:			104mT
- 	Our design @ 5MeV/m:		  77mT
- 	TESLA @25 MeV/m:		110mT
- 	TESLA @35 MeV/m:		160mT

***RF separated K******+****** beam***

_*A*_* recent 1-cell test result*

- Q

*P* (MeV/m)

*Have similar results on 2 other small structures, but still need to improve *
*(And have lots of tricks to try for that)*

## Detection

***What We Want:***

***What We'll Get:***

***Br = 63.5%***
***Also K******+************+*********

***Br = 21.2%***

_***Kinematics***_

_****__***+***__*** Veto***_

_****__*** ***__***Veto***_

_***Charged Veto***_
_***Low Material***_

- Momentum,
- direction & position
- of K+ and +

## Detection

- _Redundant measurements essential_

## Tracking vs. RICHs

## Straw Tubes

- Mechanical stress and leak rate testing
- 	2 x 10-7 atm-cc/sec-straw (N2)
- Fe55 source used to locate active region, wires
- 	Typically  0.002" from nominal
- Ru106 source to measure drift times

**20 straw prototypes**
**testing in Lab 3**

## Photon Veto System

**Small prototypes studied**
** **
**2 sector (0.3%) prototype being built now**
** **
**Tagged e****-**** beam test at Jlab Sept/Oct**

- 20 layers
- scintillator
- per PMT
- 4 PMTs per
- sector in VVS
- ~4200 PMTs
- in entire  veto
- system

## K+  0+ Veto Test

**hypothesis in an early special / engineering run**

**K****+**** ******** ********0********+***** Veto Test***

**We use the factorization to estimate the K****+**** ******** ********0********+**** background; i.e., we multiply overall ********0**** veto inefficiency of 1.6 x 10****-7**** by our kinematic rejection factor of 1/30000 **

- BNL E787
- has tested
- factorization
- by plotting
- P(+) line
- in K+  +0
- with (a) no 
- veto cuts, (b)
- online  veto
- cuts, (c) full
- analysis cuts

## Electronics / DAQ

**50MHz debunched beam ******** need continuous deadtimeless digitization**
**TDC every (~30000) channel, QDC on ********, ********+**** vetos (~8000 channels)**
**Recent history of detector activity is important**

*Imagine 2 K**+****+****0** events *
*10ns ** PMT deadtime apart*

- (*Branching Ratio*)2 / (*Number of **** veto channels*)2
- 	**= **2 x 10-8  >>  8 x 10-11 *Br we want to measure*

- Studying triggerless DAQ  (just say yes
- and trigger at level 3 in software)

****

## And at the end...

- M2MISS = M2K(1 - p/pK) + m2(1 - pK/p) – ppK2

## Spares

## Br(K+  ) = 
+{[ I(VtdVts*) X(Mt/MW) ]2   CPV top loops 
       +[ R(VtdVts*) X(Mt/MW)    CPC top loops
         +R(VcdVcs*) P(Mt,s()) ]2}
                        Charm contribution; P = 0.42  0.06

+ =0.901 

******+**{**[ ****I**(VtdVts*) **X**(Mt/MW) **]****2**   *CPV top loops*
**       ****+[ ****R**(VtdVts*) **X**(Mt/MW)    *CPC top loops*
-  **        ****+****R**(VcdVcs*) **P**(Mt,s()) **]****2**}
-  *                       **Charm contribution; P = 0.42 **** 0.06*
******+ ****=0.901**** **

**K****+**** ******** **************

- Known to _+_2.5%

*Charm contribution adds ~3% error in Br  for any given**** ******I ****(V**td**V**ts*****)*

- With current VCKM values
**Br(K****+ ******** ****************) =(0.81********0.15)x10****-11**
**(Hocker et.al., 2001)**

**(Buchalla & Buras)**

## RF separated K+ beam

## Preliminary Specs

- 3.9 GHz, TM110 mode
- 15mm iris radius
- 47mm equator radius
- 38mm cell  length
- 26 cells per meter
- 5 MeV/m Pkick;   15 MeV/station
- Epeak= 19MV/m       Bpeak= 77mT
- Transverse shunt impedance 702 /m
- Q x RSURF  is 228
- Stored energy 0.73 J/m
- 8.5 W/m dissipated into LHe
- 1.8 ~ 2.0 K
- Q:		2.2 x 109   (unloaded)
- 			6.0 x 107   ( loaded )

## Measuring the K+

**UMS - high rate PWCs**
- 2 stations of 6 planes each
- Rate ≲ 0.90 MHz/cm2 – compare
- 	HyperCP rates of 0.75 MHz/cm2
**K****+**** RICH - velocity spectrometer**
- 10m long N2 radiator @ 1.1atmospheres
-      with ~10 detected photons
- 22GeV beam gives K+ resolution in () to _+_0.5%

## Measuring the +

******20m long Ne RICH @ 1atmosphere:**

******Straw Tube tracker:**

## K+, + RICHs

- 22GeV beam gives K+ resolution in () to _+_0.5%
- K+ RICH is 10m long CF4 (or N2) radiator with ~10 detected photons
- + RICH is 20m long Ne radiator with 3000 PMTs
- Challenges include:
- Need 02 contamination at O(10-6)
- Low mass mirrors
- High rate (~1MHz) photomultiplier tubes
- Gaussian tails in resolution to 5 orders of magnitude
- Drawing heavily on the SELEX experience

## SELEX RICH

## Photon Veto System

- Design assumes the demonstrated performance
- of BNL-E787 system (1mm Pb / 5mm Scintillator)
- for vetoing low energy (20 - 200 MeV) photons

** ********angle and E(********) correlated in K****+********+********0**
** ****  ******** ****50% coverage**
** **
** ****E(********) > 1GeV in VVS ********+********0 ****events critical **

## Photon Veto System

**seconds of undetected dead time in**
**two years of data taking blows the**
**inefficiency budget**

***Photon Veto System***

**Small prototypes studied**
** **
**2 sector (0.3%) prototype being built now**
** **
**Tagged e****-**** beam test at Jlab Sept/Oct**

** ****Events with an E(********) > 1GeV in VVS have the ********enter at ~30 mrad angle**
** **
** ****GEANT simulation says 3 x 10****-5 ****inefficiency can be achieved over 1GeV**
** **
** ****Photoproduction effects (e.g., ********Pb ******** ********K****0****) in**
**  ****> 1GeV region:  Total cross section ~4mBarn**
** ******** ****4 x 10****-5**** inefficiency – but most of those final states will be detected**
** **
**Engineering problems are formidable!**

## + Veto

**Need to reject 14-20GeV ********+**** from K****+********2**** decays at ****O ****(10****-5****) level**
** **
**What could make a ********+**** fake a ********+**** ?**
** ********+**** bremsstrahlung**
** ********+**** ********e****+******
** ****DIS **
**Tested a 26 layer (41mm Fe) / (10mm scintillator) 0.6 x0.6 meter prototype in Nov 2000 at IHEP(Protvino) with ~19GeV momentum analyzed ********+**** beam:**
** ****12 x 2 segmentation**
** ****After cuts on shower shape,**
**  ************ ****acceptance (3~4) x10****-6****, with**
**  ************  ****acceptance 75.3%**
** ****Corresponding GEANT numbers**
**  ****are 2 x10****-6****, 69%**