\documentclass{chowto}

\title{Hall C Superharp System}
\howtotype{reference} % ``expert'', ``user'', ``reference''
%\experiment{Name of experiment} % Optional
\author{C. Yan}
\category{beamline} % Subject area of this document
%\maintainer{Name of person maintaining document} % Optional
\date{July 17, 2003} % Can use \today as the argument

\begin{document}

\begin{abstract}
A system documentation of Hall C superharps is briefly summarized.  It
could serve as system check list, maintenance \& survey  reference, and
upgrade  consideration for users, maintenance team, and new owners 
during the transition period of ownership change. 

For information on normal operation of the Superharp system, see
the Howto ``Superharp Operation''\cite{howto:superharp}.
\end{abstract}
\nocite{howto:superharp}.
\section{Layout of Hall C Superharps}



Group \#1  IHA3C07A and IHA3C07B

Location:            Hall C line 1-st granite table
Station \#:           4075
Wire material:    22  tungsten
Wire structure:   x1 – y – x2
Space between: 2.5 m
Type of fork:       Polyemeade, replaceable 

Pickup type:       Secondary electron (sensor wire)
                           Radiation (115M PMT)

Function:            Absolute beam position
                           Incident angle
                           Beam energy measurement
                           Acromat verification
                                      Beam emittance  measurement
                                      Beam slow motion


Group \#2 IHA3C12A and IHA2C12B

Location:            Hall C line 2-nd granite table
Station \#:           4140
Wire material:    22  tungsten
Wire structure:   x1 – y – x2
Space between: 1.63 m (?)
Type of fork:      Polyemeade, replaceable   

Pickup type:       Secondary electron (sensor wire)
                           Radiation (115M PMT)

Function:            Absolute beam position
                           Incident angle
                           Beam energy measurement
                           Achromat Optics verification
                           Energy spread
                           Beam emittance
                                      Beam slow motion



Group \#3 IHA3C17A and IHA3C17B

Location:            Hall C line 3-rd granite table
Station \#:           4220
Wire material:    30  carbon fiber (IHA3C17A)
                          22  tungsten       (IHA3C17B)
Wire structure:   x1 – y – x2
Space between: 1.88 m
Type of fork:      Polyemeade, replaceable

Pickup type:       Secondary electron (sensor wire)
                           Radiation (115M PMT)

Function:            Absolute beam position
                           Outgoing angle
                           Beam energy measurement
                           Achromat verification
                                      Beam halo (other two PMTs)                                
                                      Beam emittance 
                                      Beam slow motion



      4.  Group \#4 IHA3H00 and IHA3H00A
      
Location:            Hall C line target girder
Station \#:           4350
Wire material:    22  tungsten     
Wire structure:   x1 – y – x2
Space between  2 m
Type of fork:       Polyemeade, replaceable

Pickup type:       Secondary electron (sensor wire)
                           Radiation (115M PMT)

Function:            Absolute beam position on target
                           Incident angle
                           Target raster size and uniformity                             







Group \#5  IHA3HG0  and IHA3HG0A

Location:            Hall C line G0 target girder
Station \#:           12.5 m downstream Hall C pivot
Wire material:    22  tungsten     
Wire structure:   x – y 
Space between  2 m
Type of fork:       fixed metal

Pickup type:       Secondary electron (sensor wire)
                           Radiation (115M PMT)

Function:            Absolute beam position on G0 target
                           Incident angle
                           Target raster size and uniformity                             
                                 Beam halo


6.  Group \#6 Polarized Target IHA3H00 and IHA3H00A


Location:            Hall C line polarized target girder
Station \#:           4350 (replacement of Hall C target girder)
Wire material:    22  tungsten     
Wire structure:   x – y 
Space between  2 m
Type of fork:       Polyemeade, non-replaceable

Pickup type:       Secondary electron (sensor wire)
                           Radiation (Hamamatzu 931B PMT)

Function:            Absolute beam position on polarized target
                           Incident angle
                           Target raster size and uniformity  (Gen asked
                           2 cm raster size)                           
                                 Beam halo


\section{Electronics of Hall C Superharps} 

Electronics in Hall C Blue Rack \#HC01Z06

Harp Power Distribution
Stepper Motor Interface Chassis
Harp Preamp Power Supply
Hall C Harp CAMAC Crate
-     HP Harp Trigger Generator (CAMAC crate slot \#23)
               -    Series controller (CAMAC crate slot \#24/25, Jorway L2)

 Slot and Channel Assignment in Hall C Harp CAMAC Crate 

                                                              Wire Pickup         Radiation Pickup
ID\#           Micro           Input           PGA         ADC        PGA        ADC       
               Stepper       register        1008        5333B      1008        5333B


             Slot  Chan  Slot Chan  Slot Chan  Slot Chan  Slot Chan Slot Chan

        3C07A      16  J2A       19     1     10      1      13   J1-0      9      1      13  J2-16
        3C07B      16  J2B       19     2     10      2      13   J1-2      9      2      13  J2-17

        3C12A      16  J1A       20     1     10      3      13   J1-4      9      3      13  J2-18
        3C12B      16  J1B       20     2     10      4      13   J1-6      9      4      13  J2-19

        3C17A      17  J2A       21     1     10      5      13   J1-8      9      5      13  J2-20
        3C17B      17  J2B       21     2     10      6      13   J1-10    9      6      13  J2-21
              
        3H00        17  J1A       22      1    10      7      13   J1-12    9      7      13  J2-22
        3H00A      17  J1B       22      2    10      8      13   J1-14    9      8      13  J2-23


Electronics in Hall C Blue Rack \#HC01Z17

Harp Power Distribution
Stepper Motor Interface Chassis
Harp Preamp Power Supply
Hall C Harp CAMAC Crate
HP Harp Trigger Distributor (CAMAC crate slot \#7)
-    Series controller (Kinetic System 3952-L2, slot \# 24/25)
  
Slot and Channel Assignment in G0  Harp CAMAC Crate 

                                                                     Wire Pickup Only         
ID\#           Micro                 Input               PGA             ADC           
               Stepper             register            1008            5333B      

             Slot  Chan        Slot Chan       Slot Chan      Slot Chan  

        3G00        16     J2A          19     1            10      1          13   J1-0            
        3G0A       16      J2B         19      2            10      2          13   J1-2     
     


Driving and Encoder System

-  Counts per turn                          65536
-  Turns of full range                      64
-  Accuracy                                     1 part in 65535
-  Repeatability                                LSB
-  Configuration                             Electromagnetic resolver 
           -  Pitch of lead screw                    2.54 mm
           -  Motion Range                            76.2 mm ( 16 bit)
           -  Stepper motor                           SLO-SYN M063-LF-401
           -  Interface                                    MS 40 Microstepper
           -  Microstep size                           1/256 step
           -  Microsteps per revolution          51200
           -  Microsteps per 16 bit                 25
           -  Used encoder range                  16 bit (eliminate highest and
                                                                lowest bit)
-  Readout unit of encoder            16 bit (for survey record)
 


Connection between PMT signal cable and PGA (slot \#9)

PMT ID                        Central Pin                      Cable Shielding

3C07A                            2A                                 1A  1B (short)
3C07B                            2C                                 1C  2B (short)

3C12A                            5A                                 4A  4B (short)
3C12B                            5C                                 4C  5B (short)

3C17A                            9A                                 8A  8B (short)
3C17B                            9C                                 8C  9B (short)

3H00                            12A                              11A  11B (short) 
3H00A                         12C                              11C  12B (short)








\section{Offset Adjustment Before Fiducialization}

\begin{enumerate}
\item  To make the full range of encode readout match harp motion range,
        (16 bit covers 3 inches) an additional procedure of encoder offset
        adjustment should be done before fiducialization.
      
\item  Connect encoder with encoder interface black box by flat cable. 

\item  Move the harp manually to upper position limit switch (full retracted), 
       Loose the screw of coupler at motor side, then manually rotate shaft 
       until the display is less than 0600 (decimal data = 1280). Then tight
         the screw and record the readout data.

\item  Move the harp manually to down limit switch position. The readout should
  be less than E900 (decimal = 59648). 
Conversion coefficients from binary readout (Hexadecimal) to decimal data: 
 
       Hexadecimal encoder display                      Decimal data
       
       X1         X2          X3          X4                                         4096  X1  + 256  X2 + 16  X3 +   X4

        The resultant value of Xi in the binary data of the latches are: 0[0], 1[1],
        2[2], 3[3], 4[4], 5[5], 6[6], 7[7], 8[8], 9[9], A[10], B[11], C[12], D[13], E[14],
        F[15].
   
\end{enumerate}






\section{Upgrade Requirement from Experiments}
   
\begin{enumerate}
%Priority \#1
\item Normalize software of all Hall C superharps in 16 bit in order
                         to convert survey data 
 -  Solution: take a 16 bit channel as reference, normalize others


\item Sensor wire  
-  G0 team wants to measure 40 A beam profile directly.
         -  Solution:  G0 superharps need carbon wire (Icritical ~ 49 A at 1cm/s)


\item Preamplifier 
-  Defect rate ~ one per year because of radiation degrade of 
            electrometer chip AD 549 (high noise, large offset)
-  Solution:  Move preamp box down to the floor and place shielding
                     surround box. More effective decoupling from motor.


\item Trigger generation
-  Synchronized with line, helicity or in stand-alone model
         -  300 Hz trigger frequency came from Lebedev’s request for fast 
            emittance measurement. Users want to return to 60 Hz if this is not
            necessary now.
         -  Solution:  Hall C sync generator (manual) /AES VME module (EPICS)?

  
\item Halo measurement
-  Needs see 5 – 6 decade dynamic range counts
         -  Solution:  Reduce scan velocity


\item Ultra-low beam current profile measurement
-  Polarized target experiments need good profile in front of target at 50 ~
  100 nA  rastered beam (d = 2 cm). 
         -  Solution: Use radiation pickup channels, reduce scan velocity by 10.
         -  Problem: PGA and LeCroy HV are out of EPICS control.


\item  Unify coordinate of profile display 
-  MCC profile package gives a quick display of profile but the position
   coordinate is different to absolute encode readout and the fitting code 
           doesn’t work well for irregular beam shape
        -  Solution:  Modification of original code
\end{enumerate}

\end{document}


