By email:

Note chemical analysis is TIO_FERMI2.pdf

Chris,

I have attached the chem analysis of our LiH.

Alan

Alan Bross
(630) 840-4880 (Office)
(630) 667-3061 (Cell)
(630) 840-3061 (FAX)

From: "chris.rogers@stfc.ac.uk" <chris.rogers@stfc.ac.uk>
Date: Wednesday, September 17, 2014 at 10:21 AM
To: Alan Bross <bross@fnal.gov>, Victoria Blackmore <V.Blackmore1@PHYSICS.OX.AC.UK>, Ken Long <K.Long@imperial.ac.uk>
Cc: Pavel Snopok <snopok@gmail.com>, Daniel Kaplan <kaplan@iit.edu>, Christopher Hunt <christopher.hunt08@imperial.ac.uk>, Jaroslaw Pasternak <j.pasternak@imperial.ac.uk>, Mark Palmer <mapalmer@fnal.gov>, Maura Barone <maura@fnal.gov>, Jean-Baptiste Lagrange <j.lagrange@imperial.ac.uk>, Gene Kafka <gtkafka@gmail.com>
Subject: Re: LiH density? (HIGH PRIORITY)

It's my fault, I knew about it but did not implement this.

I added the Lithium Hydride as a MICE material to the MAUS trunk, as
MICE_LITHIUM_HYRDIDE. I set density to 0.69 g/cm^3, assume mass
fractions are as per pdg (Li:0.126797, H:0.873203) and use the Geant4
default isotopic abundance for e.g. Lithium. Let me know if you have a
better specification. A technical note would be ideal.

The usual test suite is running...

Cheers,
Chris

On 17/09/14 15:57, Alan D Bross wrote:

    Victoria et al.,

    For the purposes of our simulations, the LiH density should be set at
    0.69 g/cm^^3.  That is what has been measured for the disk
    that we will use in the experiment.  The disk was x-ray’d and is uniform
    in density (no voids).   The other disks in Gene’s report (*Gene is*
    *it a MICE note yet?)* where small sample disks that came from a
    different mold and press.  Dan is correct - this material is made
    via hot-isotastic pressing.  If I remember correctly, the spec there is
    150C and 750 psig, but I will have to look that up.  I have found
    various numbers for the “intrinsic” density of LiH (.76-.82).  We should
    not use the PDG number.

    One thing that worries me now, it that Y12 always claimed that their
    material reached 98% of the intrinsic property of LiH.  The density
    of the MICE disk seems to fall outside that spec.  It does not really
    matter for MICE, but we may be procuring additional disks from them.

    Regards,
    Alan

    Alan Bross
    (630) 840-4880 (Office)
    (630) 667-3061 (Cell)
    (630) 840-3061 (FAX)

I got a complaint from Chris Hunt that the energy loss was rather large. I note that MAUS reports the density is correctly update (Geant4 calculates the mass of material in ratio new_mass/old_mass = 0.8414634146341463 = 0.69/0.82.

I tried tracking through 65 mm cylinder of LiH, output px distribution and energy distribution as below:

Energy loss is indeed coming through rather large. I have no feel for what is correct.

By email, from Chris Hunt:

Hi Chris,

Just had a read through the patch you sent - should the numbers in the
lines:

miceLiH->AddElement(elMiceLi, 0.126797);
- and -
miceLiH->AddElement(elH, 0.873203);

both be equal to 1?
It looks like the other functions add elements according to the their
fraction in the molecular formula. I'm not actually sure what numbers
you've used there?

Cheers

Chris

This is the mass fraction of Lithium to Hydrogen in Lithium Hydride material

http://pdg.lbl.gov/2014/AtomicNuclearProperties/HTML/lithium_hydride_LiH.html

The function call is

//
// Add an element or material, giving fraction of mass
//
void AddElement (G4Element* element ,  //the element
                 G4double   fraction); //fractionOfMass

I note there is also

//
// Add an element, giving number of atoms
//
void AddElement(G4Element* element,   //the element
                G4int      nAtoms);   //nb of atoms in
                                      // a molecule

Might make more sense because presumably the mass fraction will change with odd isotopes? I gave it a go, the results look more sane...

I think this is okay now