Question: where is radiation produced in the xray tube
[{'answer': 'the anode material', 'provenance': [{'wikipedia_id': '907899', 'title': 'X-ray tube', 'start_paragraph_id': 7, 'start_character': 398, 'end_paragraph_id': 7, 'end_character': 416, 'bleu_score': 1.0, 'section': 'Section::::Physics.\n'}]}, {'provenance': [{'wikipedia_id': '907899', 'title': 'X-ray tube', 'start_paragraph_id': 8, 'start_character': 0, 'end_paragraph_id': 8, 'end_character': 1299, 'bleu_score': 0.936466411091559, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10445767516907888643}, 'section': 'Section::::Physics.\n'}]}]