Source Code for Module reflectometry.reduction.ncnr_ng7

  1  # This program is public domain 
  2  """ 
  3  Data file reader for NCNR NG-7 data. 
  4   
  5  """ 
  6   
  7  import os, numpy 
  8  from reflectometry.reduction import icpformat 
  9  from reflectometry.reduction import refldata 
 10  from reflectometry.reduction import properties 
 11   
 12   
 13  # Instrument parameters 
 14  # As instrument parameters change add additional lines to this file 
 15  # indicating the new value and the date of the change.  The order of 
 16  # the entries does not matter.  The timestamp on the file will 
 17  # determine which value will be used. 
 18  # The format of the entries should be: 
 19  #      default.NAME = (VALUE, 'YYYY-MM-DD')  # value in effect after DD/MM/YYYY 
 20  #      default.NAME = (VALUE, '')          # value in effect at commissioning 
 21  default = properties.DatedValues() 
 22  default.wavelength = (4.76,'')  # in case ICP records the wrong value 
 23   
 24  # Detector saturates at 15000 counts/s.  The efficiency curve above 
 25  # 15000 has not been measured. 
 26  default.saturation = (numpy.array([[1,15000,0]]),'') 
 27   
 28   
 29  # NG-1 detector closer than slit 4? 
 30  default.detector_distance = (2000., '') # mm 
 31  default.psd_width = (100, '') # mm 
 32  default.slit1_distance = (-75*25.4, '') # mm 
 33  default.slit2_distance = (-14*25.4, '') # mm 
 34  default.slit3_distance = (9*25.4, '') # mm 
 35  default.slit4_distance = (42*25.4, '') # mm 
 36   
 37  #    rate     correction factor 
 38  saturation = """ 
 39       304     1.0   ; 
 40      1788     1.0074; 
 41      6812     1.0672; 
 42     13536     1.1399; 
 43     19426     1.2151; 
 44     24022     1.2944; 
 45     27771     1.370 ; 
 46     31174     1.429 
 47  """ 
 48  C = numpy.matrix(saturation).A 
 49  C[1,:] = 1/C[1,:] # Use efficiency rather than attenuation 
 50  default.pencil_saturation = (C, '') 
 51  # The following widths don't really matter for point detectors, but 
 52  # for completeness we can put in the values. 
 53  default.pencil_length = (25.4*6,'') # mm TODO: Is NG-7 pencil det. 6" long 
 54  default.pencil_width = (25.4*1,'') # mm TODO: Is NG-7 pencil det. 1" wide? 
 55   
 56  # TODO: NG-7 PSD saturates at 8000 counts/s? 
 57  default.psd_saturation = (numpy.array([1,8000],'f'),'') 
 58  default.psd_minbin = (9,'') 
 59  default.psd_maxbin = (246,'') 
 60  default.psd_width = (100,'') 
 61  default.psd_pixels = (256,'') 
 62  default.monitor_timestep = (60./100,'') # s ; ICP records 1/100ths of min 
 63   
 64  # =================================================================== 
 65   
 66 -class NG7Icp(refldata.ReflData): 
 67      # Instrument description 
 68      probe = "neutron" 
 69      format = "NCNR ICP" 
 70      instrument = "NCNR NG-7" 
 71   
 72      # The following allows the user to override the wavelength 
 73      # all files in a dataset to compensate for an incorrectly 
 74      # recorded wavelength in ICP. 
 75      _wavelength_override = {} 
 76 -    def __init__(self, path, *args, **kw): 
 77          super(NG7Icp,self).__init__(*args, **kw) 
 78          self.path = os.path.abspath(path) 
 79   
 80   
 81          data = icpformat.summary(path) 
 82          if data.scantype != 'R': 
 83              raise TypeError, "Only R-Buffers supported for NG-7" 
 84   
 85          self.date = data.date 
 86          self.name = data.filename 
 87          self.description = data.comment 
 88          self.dataset = self.name[:5] 
 89   
 90          self.default = default(str(data.date)) 
 91          self.detector.distance = self.default.detector_distance 
 92          self.slit1.distance = self.default.slit1_distance 
 93          self.slit2.distance = self.default.slit2_distance 
 94          self.slit3.distance = self.default.slit3_distance 
 95          self.slit4.distance = self.default.slit4_distance 
 96          self.detector.rotation = 0 # degrees 
 97          self.monitor.time_step = self.default.monitor_timestep 
 98   
 99          #if data.count_type=='TIME': 
100          #    # Override the default monitor base of 'counts' 
101          #    self.monitor.base='time' 
102   
103          if data.PSD: 
104              self.instrument = 'NCNR NG-7 PSD' 
105              self._psd() 
106          else: 
107              self.instrument = 'NCNR NG-7' 
108              self._pencil_detector() 
109          self.display_monitor = 1 
110   
111          # Set initial Qz 
112          self.resetQ() 
113   
114          # Callback for lazy data 
115          self.detector.loadcounts = self.loadcounts 
116   
117   
118 -    def _pencil_detector(self): 
119          """ 
120          Pencil detector on NG-7. 
121          """ 
122          self.detector.saturation = self.default.pencil_saturation 
123          self.detector.width_x = self.default.pencil_length 
124          self.detector.width_y = self.default.pencil_width 
125          self.detector.center_x = 0 
126          self.detector.center_y = 0 
127          self.detector.rotation = 0 
128   
129 -    def _psd(self): 
130          """ 
131          PSD on NG-7. 
132          """ 
133          self.detector.saturation = self.default.psd_saturation 
134          width = self.default.psd_width 
135          minbin,maxbin = self.default.psd_minbin,self.default.psd_maxbin 
136          pixels = self.default.psd_pixels 
137          self.detector.width_x = numpy.ones(pixels,'f')*(width/(maxbin-minbin)) 
138          self.detector.center_x = 0 
139          self.detector.width_y = self.default.psd_height 
140   
141 -    def loadcounts(self): 
142          data = icpformat.read(self.path) 
143          return data.counts 
144   
145 -    def load(self): 
146          data = icpformat.read(self.path) 
147          self.detector.wavelength \ 
148              = data.check_wavelength(self.default.wavelength, 
149                                      NG7Icp._wavelength_override) 
150   
151          if 'qz' in data: 
152              # NG7 automatically increases count times as Qz increases 
153              monitor, prefactor = data.monitor,data.prefactor 
154              Mon1, Exp = data.Mon1,data.Exp 
155              Qz = data.column.qz 
156              automonitor = prefactor*(monitor + Mon1 * abs(Qz)**Exp) 
157              if data.count_type == 'NEUT': 
158                  self.monitor.counts = automonitor 
159              elif data.count_type == 'TIME': 
160                  self.monitor.count_time = automonitor 
161              else: 
162                  raise ValueError, "Expected count type 'NEUT' or 'TIME' in "+self.path 
163   
164          if 'monitor' in data: 
165              self.monitor.counts = data.column.monitor 
166          if 'time' in data: 
167              self.monitor.count_time = data.column.time*60 
168   
169          self.monitor.base = 'counts' if self.monitor.counts is not None else 'time' 
170   
171          if 's1' in data: self.slit1.x = data.column.s1 
172          if 's2' in data: self.slit2.x = data.column.s2 
173          if 's3' in data: self.slit3.x = data.column.s3 
174          if 's4' in data: self.slit4.x = data.column.s4 
175          if 'qz' in data: 
176              Qx = data.column.qx if 'qx' in data else 0 
177              Qz = data.column.qz 
178              A,B = refldata.QxQzL_to_AB(Qx,Qz,self.detector.wavelength) 
179              self.sample.angle_x,self.detector.angle_x = A,B 
180   
181          # Set initial Qz 
182          self.resetQ() 
183   
184          # TODO: if the dataset is large, set up a weak reference instead 
185          self.detector.counts = data.counts 
186